Air conditioning system using outdoor air, indoor air unit, and outdoor air unit thereof, and stack

ABSTRACT

An air conditioning system using outdoor air has a first heat exchanger, an evaporator, a condenser, and a first fan disposed on the interior side; and a second heat exchanger and a second fan disposed on the exterior side. An expansion valve and a compressor are further provided. An air conditioner has a first piping connected to the evaporator, the condenser, the expansion valve, and the compressor, for circulating a first refrigerant to perform a compression-type refrigeration cycle. An indirect outdoor air cooler has a second piping connected to the first heat exchanger and the second heat exchanger for circulating a second refrigerant to induce a heat exchange in the first heat exchanger between the second refrigerant and the indoor, and to induce a heat exchange in the second heat exchanger between the outdoor air and the second refrigerant.

TECHNICAL FIELD

The present invention relates to an air conditioning system using outdoor air.

BACKGROUND

For example, a large number of servers have been installed in server rooms of data center or enterprises. The room temperature in such server rooms rises due to heat generation by a large number of servers and such increase in room temperature can result in malfunction or damage of the servers. For this reason, an air conditioning system has been used to maintain a constant temperature inside the entire room. Such air conditioning system operates practically at all times, even in winter.

In order to stabilize the temperature in the server room, the conventional air conditioning system designed for such server room uses a circulation system such that the low-temperature air (cold air) blown from an air conditioning device and supplied into the server room flows in contact with a server on a server rack, thereby cooling the server, and the air (warm air) warmed up by the heat of the server is returned from the server room into the air conditioning device and cooled in the air conditioning device to obtain again the cold air that is blown therefrom and again supplied into the server room.

For example, the conventional techniques relating to such a system are described in Patent Documents 1 and 2.

The invention disclosed in Patent Document 1 provides an air conditioner that can operate in an energy saving mode and a temperature-humidity controllability mode, while ensuring sufficient high-frequency protection.

The invention disclosed in Patent Document 2 provides an air conditioner in which good temperature controllability can be obtained by suppressing interior temperature fluctuations caused by changes in the number of operating units and which can operate in an optimum mode designed with sufficient consideration for energy saving ability, while ensuring sufficient high-frequency protection.

-   Patent Document 1: Japanese Patent No. 3361458 -   Patent Document 2: Japanese Patent No. 3320360

DISCLOSURE OF THE INVENTION

FIG. 14 shows an example of the conventional indirect outdoor air cooling system.

In FIG. 14, the indirect outdoor air cooling system is designed to cool any interior space and uses outdoor air for cooling, without introducing the outdoor air into the interior space. The interior space is, for example, a server room having installed therein a server rack 202 carrying heating elements 201 such as server devices (computer devices) or the like. In such interior space, a large amount of heat is generated by a large number of heating elements 201, and the interior space should be cooled even in winter.

In this example, the interior space is divided into a space of server setting, an under-floor space, and an attic space. Among them, the space of server setting is the space where the server rack 202 carrying the heating elements 201 is installed. The ceiling is above the space of server setting and the floor is therebelow. The space above the ceiling is the attic space, and the space below the floor is the under-floor space. Naturally, holes are present in the floor and ceiling, and the cold air or warm air flows into the space of server setting and therefrom.

In the indirect outdoor air cooling system shown in the figure, the return air (warm air), for example, from the server room, is cooled by a typical air conditioning device 210, but energy consumption is reduced by decreasing the temperature of the return air by using the outdoor air at the stage before the air conditioning device.

The air conditioner 210 constituted by a refrigerator 211, an air handling unit 212, an expansion valve 213, and a refrigerant piping 214 shown in the figure is well-known typical air conditioner. Thus, the air conditioner 210 is a typical air conditioner (air conditioning device) that performs cooling in the following typical compression-type refrigeration cycle (vapor compression type refrigeration cycle or the like) by using a refrigerant: “evaporator→compressor→condenser→expansion valve→evaporator”.

The refrigerant circulates through the refrigerant piping 214 in the refrigerator 211, air handling unit 212, and expansion valve 213. The refrigerator 211 has a compressor, a condenser, and a fan. The air handling device 212 has an evaporator and a fan.

The air handling unit 212 delivers cold air into the under-floor space in the interior space and supplies the cold air through the under-floor space into the space of server setting. The cold air is heated by cooling the heating elements 201, and the warm air flows from the space of server setting into the attic space. With the usual cooling system, the warm air is caused to flow from the attic space into the air handling unit 212 through a duct or the like. The air handling unit 212 generates the cold air by cooling the inflowing warm air with the evaporator.

The air handling unit 212 cools the inflowing warm air so that the temperature of the cold air assumes a predetermined value (set value), and it is obvious that the load required for cooling rises and power consumption increases as the temperature of the inflowing air rises. Accordingly, with the object of saving the energy, the indirect outdoor air cooler 220 is provided to reduce the temperature of the warm air flowing into the air handling unit 212.

A wall 1 shown in the figure is that of any building, and the exterior of the building is separated from the interior thereof by the wall 1 as a boundary. The interior of the building includes not only the interior space where the server is installed, but also the space where the air handling unit 212 is provided (in the example shown in the figure, it can be the space adjacent to the interior space, for example, a machine room). The air in the interior of the building (indoor air) circulates inside the building, while repeatedly assuming the state of the cold air and warm air. The air in the exterior of the building (outdoor air) may be lower in temperature than the indoor air in the warm air state, provided that the season is other than summer.

The indirect outdoor air cooler 220 has a heat exchanger 221, a fan 222, a fan 223, an indoor air duct 224, and an outdoor air duct 225. The indoor air duct 224 is provided such that one end thereof is at the attic space side and the other end thereof is at the air handling unit 212 side. The indoor air duct is connected along the way to the heat exchanger 221. The warm air of the attic space in blown by the fan 222 into the indoor air duct 224 and also discharged to the air handling unit 212 side, but passes along the way through the heat exchanger 221.

Further, holes are provided in two random locations of the wall 1 (one will be referred to as an outdoor air inflow hole 226 and the other as an outdoor air discharge hole 227). One end of the outdoor air duct 225 is connected to the outdoor air inflow hole 226 and the other end is connected to the outdoor air discharge hole 227. The outdoor air duct 225 is connected along the way to the heat exchanger 221. The outdoor air is caused by the fan 223 to pass through the outdoor duct 225. Thus, the outdoor air is caused to flow in from the outdoor air inflow hole 226 and discharged from the outdoor air discharge hole 227, but the outdoor air passes along the way through the heat exchanger 221.

As mentioned hereinabove, in the conventional indirect outdoor air cooling system, the indirect outdoor air cooler 220 is newly added to the already installed typical air conditioner 210, and the installation space is increased accordingly. Further, the ducts (indoor air duct 224 and outdoor air duct 225), which are shown in the simplified manner in the figure, actually take a large installation space. The amount of power consumed by the fan 222 and the fan 223, although being comparatively small, is also added. In addition, the installation of the indirect outdoor air cooler 220 such as shown in FIG. 14 is time consuming and costly.

As mentioned hereinabove, the indoor air (warm air) and outdoor air pass through the heat exchanger 221, and heat is exchanged between the indoor air (warm air) and outdoor air inside the heat exchanger 221. Where the heat exchanger 221 is used, the heat exchange is performed while the outdoor air is separated from the indoor air. As a result, the outdoor moisture, dust, and corrosive gases contained in the outdoor air are not introduced into the interior space and, therefore, the reliability of electronic devices such as servers can be maintained. Further, such heat exchanger 221 is of a well-known configuration which is not described in detail herein.

Where the temperature of the indoor air is reduced by the heat exchange in the heat exchanger 221, the temperature of the warm air flowing into the air handling unit 212 decreases, and power consumption in the air conditioner 210 is lowered (energy saving effect is obtained). The power consumption in the fan 222 and the fan 223 may be assumed to be comparatively small.

The indoor air is cooled by the outdoor air to decrease the temperature of the indoor air (warm air) essentially only when “the temperature of the indoor air (warm air)>the temperature of the outdoor air”. Therefore, in a state in which the temperature of the outdoor air is low, as in the winter, the effect of cooling the indoor air (warm air) with the heat exchanger 221 is high and, therefore, the energy saving effect in the air conditioner 210 is high. Meanwhile, in the summer, the effect of cooling the indoor air with the heat exchanger 221 is small, or no effect is obtained, or even the reverse effect can be obtained. There are also regions in which the outdoor air temperature is very high through almost the entire year, as in hot climate zones, regardless of the season.

Thus, the main problem associated with an air conditioning system that cools the space where heating elements are present, such as a server room, in particular, an air conditioning system designed to save energy by using the outdoor air, is how to enable the use of the outdoor air for cooling the interior space and save the energy even when the outdoor air temperature is high. In addition to this main problem, other problems are associated with additional energy saving, size reduction, and cost reduction.

The present invention relates to an air conditioning system that cools the interior space by using outdoor air to save energy, and an object of the present invention is to provide an air conditioning system using outdoor air that can realize the indoor air cooling by using the outdoor air even when the outdoor air temperature is high and can save energy in an air conditioning system with a compression-type refrigeration cycle, and also to provide an indoor air unit and an outdoor air unit for such air conditioning system.

The air conditioning system using outdoor air in accordance with the present invention comprises a configuration provided at the interior side (inside the building) and a configuration provided at the exterior side (outside the building). The air at the interior side, in particular the return air (warm air) from the cooling object space, is taken as the indoor air. The air at the exterior side is the outdoor air.

A first heat exchanger, an evaporator, a condenser, and a first fan for passing the indoor air through the first heat exchanger, evaporator, and condenser are provided at the interior side.

A second heat exchanger and a second fan for passing the outdoor air through the second heat exchanger are provided at the exterior side.

In addition, an expansion valve and a compressor are provided. The expansion valve and compressor are each provided either at the interior side or at the exterior side.

The system is arranged in the order of the condenser, first heat exchanger, and evaporator from the upstream side of a flow of the indoor air formed by the first fan. Therefore, the indoor air first passes through the condenser, then passes through the first heat exchanger and finally passes through the evaporator.

Additionally provided is a first piping connected to the evaporator, condenser, expansion valve, and compressor. An air conditioner of a compression-type refrigerant cycle is configured by circulating a first refrigerant in the first piping through the evaporator, condenser, expansion valve, and compressor.

Additionally provided is a second piping connected to the first heat exchanger and the second heat exchanger. A second refrigerant (for example, cooling liquid such as water) is circulated in the second piping through the first heat exchanger and the second heat exchanger.

An indirect outdoor air cooling system includes the first heat exchanger, the second heat exchanger, and the second refrigerant. Thus, the indoor air is cooled by the second refrigerant by causing the second refrigerant to exchange heat in the first heat exchanger with the indoor air that has passed through the condenser. The second refrigerant is cooled by the outdoor air by causing the indoor air to exchange heat with the cooled second refrigerant and the outdoor air in the second heat exchanger.

Here, the condenser radiates heat received by the evaporator from the surroundings (indoor air) and is usually installed at the exterior side (outside the building) to radiate heat to the outdoor air. By contrast, in the abovementioned configuration, the condenser is installed at the interior side (inside the building). Therefore, the temperature of the indoor air is greatly increased when the indoor air passes through the condenser. The indoor air after this increase in temperature indirectly exchanges heat with the outdoor air via the second refrigerant. Therefore, the indoor air can be cooled by the outdoor air even when the outdoor air temperature is very high.

Further, in the condenser, the refrigerant is cooled by the indoor air. Therefore, in particular under the environment in which the outdoor air temperature is higher than the indoor air temperature (temperature before the indoor air passes through the condenser), the effect of cooling the first refrigerant in the condenser is comparatively high. In other words, when the first refrigerant is cooled by the outdoor air by causing the outdoor air to pass through the condenser, as in the usual case, the effect of cooling the first refrigerant decreases under the environment in which the outdoor air temperature is very high. Further, under the environment in which “the outdoor air temperature>the indoor air temperature”, the effect of cooling the first refrigerant is higher when the indoor air is used. As a result, in the configuration of the present invention, the power consumption in the air conditioner of a compression-type refrigeration cycle is reduced by comparison with the conventional configuration at least under the above-described environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration of the air conditioning system of the first embodiment.

FIG. 2 shows the configuration of the air conditioning system of the second embodiment.

FIG. 3 is an enlarged view of part of the configuration shown in FIG. 2.

FIG. 4 shows the configuration of the air conditioning system (variation 1) of the third embodiment.

FIG. 5A shows the configuration of the first example of the air conditioning system (variation 2) of the third embodiment.

FIG. 5B shows the configuration of the second example of the air conditioning system (variation 2) of the third embodiment.

FIG. 6 shows the operation model of the air conditioning system of the third embodiment.

FIGS. 7A to 7D serve to compare the conventional configuration with that of the third embodiment.

FIG. 8 is a modification of the configuration shown in FIG. 4.

FIG. 9 is a modification of the configuration shown in FIG. 5A.

FIG. 10 is a simplified configuration diagram of the entire system including the air conditioning system of the third embodiment.

FIG. 11 shows the configuration of the air conditioning system (variation 1) of the fourth embodiment.

FIG. 12 shows the configuration of the air conditioning system (variation 2) of the fourth embodiment.

FIG. 13 shows the operation model of the air conditioning system of the fourth embodiment.

FIG. 14 shows an example of the conventional indirect outdoor air cooling system.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be explained below with reference to the drawings.

The “interior side” in the present invention means the “interior of the building”. Therefore, the “interior side” includes not only the “interior space serving as a cooling object”, but also a machine room or the like. In other words, the “interior side”, as referred to herein, can be also said to represent the space where the abovementioned “indoor air” (air inside the building) is present. Likewise, the “exterior side” in the present invention means the abovementioned “exterior of the building”. In other words, the “exterior side”, as referred to herein, can be also said to represent the space where the abovementioned “outdoor air” (air outside the building) is present. Further, the “interior space” is somewhat different in meaning from the “interior side” and is assumed to mean the below-described “cooling object space to be cooled by the indirect outdoor air cooling system (interior space that is the cooling object), and in a more narrow sense, the space of server setting included in the cooling object space.” Therefore, the “interior space” does not include the machine room or the like.

FIG. 1 shows the configuration of the air conditioning system (indirect outdoor air cooling system) of the first embodiment.

In FIG. 1, the cooling object space that is to be cooled with the indirect outdoor air system is assumed to be the same as in the conventional example shown in FIG. 14. Thus, the interior space which is the object of cooling is, for example, a server room having installed therein a rack 102 carrying heating elements 101 such as server devices (computer devices). In the present example, the space of server setting shown in the figure is divided into an under-floor space and an attic space, in the same manner as in FIG. 14. This example, which is obviously not limiting, is used in the present explanation. In this example, the cooling object can be also interpreted, in the narrow meaning thereof, as the space of server setting.

Further, similarly to the example shown in FIG. 14, the interior of the building is separated from the exterior of the building by a wall 1, and the air located inside the building (indoor air) circulates while repeatedly assuming the state of the cold air and warm air. The air in the exterior of the building (outdoor air) is essentially assumed to be lower in temperature that the indoor air in the warm air state.

Not only the interior space, but also the machine room are present inside the building. As mentioned hereinabove, the machine room is, for example, a space adjacent to the interior space and connected to the under-floor space and attic space. The below-described air handling unit 12 and indoor air unit 30 are installed in the machine room.

In a simplified scheme, a typical air conditioner 10 supplies cold air to the interior space and generates the cold air again by cooling the return air (warm air) from the interior space. However, in the present system, the temperature of the return air (warm air) is therebefore reduced by using the outdoor air.

In the example shown in the figure, the typical air conditioner 10 delivers the cold air into the under-floor space, supplies the cold air into the space of server setting via the under-floor space, and cools the heating elements 101 by the cold air. As a result, the cold air becomes the warm air, and this warm air flows into the attic space and then returns as the return air into the air conditioner 10. However, at the preceding stage of this process, the temperature of the warm air is reduced using the outdoor air in the indirect outdoor air cooler 20. The air conditioner 10 may be identical to the typical conventional air conditioner 210.

In the explanation below, the temperature of the outdoor air is presumed to be low. The statement that “the temperature of the outdoor air is low” does not indicate that the temperature of the outdoor air is equal to or lower than a certain temperature, and this low temperature depends on the temperature of the indoor air (warm air). This assumption is the same as in the conventional configuration. According to one approach, since the indirect outdoor air cooling serves to reduce the temperature of the indoor air (warm air) by using the outdoor air, the case in which the temperature of the return air (warm air) can be decreased as a result of such temperature reduction can be said to be realized when the temperature of the outdoor air is low. In one example, as mentioned hereinabove, the case in which the temperature of the outdoor air is lower than the temperature of the indoor air (warm air) is considered as the case in which “the temperature of the outdoor air is low”, but the embodiment is not limited to this example.

In this case, the configuration that delivers the cold air to the under-floor space is the typical air conditioner 10 shown in the figure. This typical air conditioner 10 is constituted by a refrigerator 11, an air handling unit 12, an expansion valve 13, and a refrigerant piping 14. Those, refrigerant 11, air handling unit 12, expansion valve 13, and refrigerant piping 14 may be the same as the conventional refrigerant 211, air handling unit 212, expansion valve 213, and refrigerant piping 214 shown in FIG. 14.

In other words, the air conditioner 10 shown in the figure may be the same as the well-known typical air conditioner, such as the conventional air conditioner 210. Therefore, the air handing unit 12 has an evaporator 12 a and a fan 12 b shown in the figure (the details of the configuration are neither shown in the figure nor explained). Further, the refrigerator 11 has not only the fan 11 a shown in the figure, but also a compressor and a condenser which are not shown in the figure.

Thus, the typical air conditioner 10 has the evaporator 12 a and the compressor (not shown in the figure), condenser (not shown in the figure) and the expansion valve 13, which are the components of the typical air conditioner, and the refrigerant circulates through the refrigerant piping 14 in those components. Thus, the refrigerant circulates in the typical compression-type refrigeration cycle (vapor compression-type refrigeration cycle or the like): “evaporator→compressor→condenser→expansion valve→evaporator”. In the evaporator 12 a, the heat is drawn by the evaporating refrigerant from the surrounding air, thereby cooling the surrounding air (inflowing warm air). The received heat is radiated by the condenser to the outdoor air. The outdoor air is blown by the fan 11 a to the condenser (not shown in the figure), and the condenser (not shown in the figure) radiates the heat to the outdoor air as mentioned hereinabove. It goes without saying, that the outdoor air is thereafter discharged to the outside of the refrigerator 11.

The wall 1 shown in the figure is that of any building, and the interior space and the space adjacent to the interior space (machine room) are present inside the building. The air handling unit 12 and the below-described indoor air unit 30 are installed in the machine room, and the refrigerator 11 and the below-described outdoor air unit 40 are installed outside the building. The indoor air circulates inside the building (interior space and machine room), while repeatedly assuming the warm air state and cold air state, and the outdoor air is present outside the building.

The typical air conditioner 10 is explained hereinabove in a simple manner, and similarly to case of the above-described conventional air conditioner 210, it is desirable that the amount of power consumed by the typical air conditioner 10 be decreased by reducing the temperature of the return air (warm air) flowing into the air handing unit 12 of the typical air conditioner 10. Even if the amount of power consumed by the typical air conditioner 10 is decreased, it is meaningless if the total power consumption is increased. As a result, a method for reducing the temperature of the indoor air (warm air) by using die outdoor air has been considered and the conventional system has been provided with the indirect outdoor air cooler 220.

By contrast, in the present example, the indirect outdoor air cooler 20 shown in the figure is provided.

The indirect outdoor air cooler 20 is explained below in greater detail.

The indirect outdoor air cooler 20 is constituted by the indoor air unit 30 and the outdoor air unit 40.

The indoor air unit 30 and the outdoor air unit 40 are, for example, individually manufactured at respective plants and then installed so as to be in close contact with the surfaces of the wall 1 (with the inner wall and outer wall, respectively, as shown in the figure).

The exterior side (outside the building) and the interior side (inside the building) are separated by the wall 1 as a boundary. The outdoor air unit 40 is installed on the exterior side, and the indoor air unit 30 is installed on the interior side. In other words, the outdoor air unit 40 is installed so as to be in close contact with the wall surface on the exterior side of the wall 1. The indoor air unit 30 is installed so as to be in close contact with the wall surface on the interior side of the wall 1.

For example, the indoor air unit 30 has a liquid-gas heat exchanger 31, a fan 32, a piping 21 (part thereof, about half), and a circulating pump 22 shown in the figure.

For example, the outdoor air unit 40 has a liquid-gas heat exchanger 41, a fan 42, and a piping 21 (part thereof, about half) shown in the figure.

When the indoor air unit 30 is manufactured at a plant, for example, the liquid-gas heat exchanger 31 and the fan 32 shown in the figure are provided inside a box-like housing which is open at one surface (this surface is absent). Further, two holes (indoor air inlet 33 and indoor air outlet 34) shown in the figure are provided in the housing. The piping 21 (piping 21 connected along the way to the circulating pump 22) shown in the figure may be already connected to the liquid-gas heat exchanger 31 when the indoor air unit is manufactured at a plant, or may be connected to the liquid-gas heat exchanger 31 at the time of installation. Alternatively, only the piping 21 may be connected at a plant and the circulating pump 22 may be connected to the piping 21 at the time of installation.

When the outdoor air unit 40 is manufactured at a plant, for example, the liquid-gas heat exchanger 41 and the fan 42 shown in the figure are provided inside a box-like housing which is open at one surface (this surface is absent).

The indoor air unit 30 and the outdoor air unit 40 are installed so that the open surfaces thereof mate with the surface of the wall 1.

Further, two holes (outdoor air inlet 43 and outdoor air outlet 44) shown in the figure are provided in the housing of the outdoor air unit 40. The piping 21 shown in the figure may be already connected to the liquid-gas heat exchanger 41 when the indoor air unit is manufactured at a plant, or may be connected to the liquid-gas heat exchanger 41 at the time of installation.

At the time of installation, through holes for allowing the piping 21 to pass therethrough should be provided in two locations in the wall 1. When the piping 21 (part thereof, about half) is already provided at the indoor air unit 30 and the outdoor air 40 during the manufacture at a plant, the “piping 21 connected along the way to the circulating pump 22”, which is shown in the figure, is formed, e.g., by welding one piping 21 to the other (at this time, the circulating pump 22 is also connected).

The indirect outdoor air cooler 20 is configured by installing the indoor air unit 30 and the outdoor air unit 40 in the above-described manner.

Since the heat exchange is performed in a state in which the outdoor air is separated from the indoor air, in the indirect outdoor air cooler 20, the heat exchange is performed while the outdoor air and indoor air are separated from each other, in the same manner as in the conventional system shown in FIG. 14. Therefore, the outdoor air moisture, dust, and corrosive gases contained in the outdoor air are not introduced into the interior space. As a result, the reliability of the electronic devices such as servers can be maintained.

As mentioned hereinabove, it is necessary that holes for the piping 21 be provided in the wall 1, but the size of the holes can be reduced by comparison with that of the holes 226 and 227 for inflow and discharge of the outdoor air, as in the conventional configuration, and the installation operation is facilitated.

In the above-described example, a total of two piece of piping 21 are used, one for conveying the refrigerant from the outdoor air unit into the indoor air unit and the other for conveying the refrigerant from the indoor air unit into the outdoor air unit, and the through holes of the wall 1 are formed in two locations. However, the embodiments of the present invention are not limited to this example. For example, it is possible to form a large through hole in one location and pass the two pieces of piping 21 through this large hole.

In the above-described example, both the indoor air unit 30 and the outdoor air unit 40 are installed so that the open surfaces thereof match the surface of the wall 1, but the embodiments of the present invention are not limited to this example. For example, it is possible to manufacture the indoor air unit 30 and the outdoor air unit 40 as an integrated indoor-outdoor air unit after welding the pieces of piping 21 at a plant, provides an orifice of the same shape as the integrated indoor-outdoor air unit in the wall 1 and embed the indoor-outdoor air unit into the wall.

The fan 32 in the indoor air unit 30 after the abovementioned installation creates the air flow (shown by a dot-dash arrow in the figure) such that the warm air of the attic space flows from the indoor air inlet 33 and passes through inside the indoor air unit 30 (in particular, inside the liquid-gas heat exchanger 31), and is then discharged from the indoor air outlet 34. Basically, the temperature of the warm air discharged from the indoor air outlet 34 is lower than the temperature of the warm air flowing in from the indoor air inlet 33.

The warm air discharged from the indoor air outlet 34 flows into the air handling unit 12 and is cooled by the evaporator 12 a inside the air handling unit 12 to become the cold air. This cold air is blown by the fan 12 b into the under-floor space. By reducing the warm air temperature as mentioned hereinabove, it is possible to reduce the power consumed in the typical air conditioner 10 by comparison with the case in which the warm air located in the attic space flows directly into the air handling unit 12.

In the outdoor air unit 40 after the abovementioned installation, the fan 42 causes the outdoor air to flow in from the outdoor air inlet 43 and pass through inside the outdoor air unit 40 (in particular, in the liquid-gas heat exchanger 41), and then creates the air flow (shown by a dot-dash arrow in the figure) such that is discharged from the outdoor air outlet 44.

In this configuration, the circulating pump 22 is connected to any location in the piping 21, and the refrigerant such as a liquid (for example, water) is sealed inside the piping. As a result, where the circulating pump 22 is operated, this liquid (for example, water) circulates in the liquid-gas heat exchanger 31 and the liquid-gas heat exchanger 41 via the piping 21. The liquid-gas heat exchanger 31 may be identical to the liquid-gas heat exchanger 41.

The liquid-gas heat exchangers 31 and 41 have well-known configurations and only briefly described below, without being explained in greater detail. In the conventional heat exchanger 221, two gases (both are the air, namely, the indoor air (warm air) and outdoor air) are caused to pass through inside the heat exchanger and heat is exchanged between the two gases, whereby the indoor air (warm air) is cooled by the outdoor air when the outdoor air temperature is low. In the liquid-gas heat exchangers 31 and 41, a liquid (for example, water) and a gas (in this case, the air) are caused to pass through inside the heat exchanger and heat is exchanged between the liquid and the gas, thereby cooling the fluid with a higher temperature.

The gas (air) is the indoor air (warm air) in the liquid-gas heat exchanger 31 and the outdoor air in the liquid-gas heat exchanger 41. Further, the liquid is water circulated by the piping 21 and the circulating pump 22.

Where the outdoor air temperature is low, the heat exchange between the liquid (water or the like) and the outdoor air in the liquid-gas heat exchanger 41 reduces the temperature of the liquid (water or the like), and the temperature of the outdoor air rises. The liquid (water or the like) with a lower temperature flows through the piping 21 into the liquid-gas heat exchanger 31. As a result, heat exchange is performed in the liquid-gas heat exchanger 31 between the liquid (water or the like) with a comparatively low temperature and the indoor air (warm air). As a consequence, the temperature of the indoor air (warm air) drops and the temperature of the liquid (water or the like) rises. Therefore, the liquid (water or the like) that has assumed a comparatively high temperature flows through the piping 21 into the liquid-gas heat exchanger 41 and is cooled again in the above-described manner by the outdoor air. As a result, the outdoor air with raised temperature is discharged from the outdoor air outlet 44.

In the configuration shown in FIG. 1, the fan 32 causes the air to flow downward (the direction from top to bottom) inside the indoor air unit 30, but the air can be also caused to flow upward (the direction from bottom to top). Likewise, in the configuration shown in FIG. 1, the fan 42 causes the air to flow upward inside the outdoor air unit 40, but the air can be also caused to flow downward.

However, it is preferred that the flow of air inside the indoor air 30 be a downward flow as shown in FIG. 1. In such a case, the warm air warmed up by the heating elements 101 is at the top, and the air cooled in the liquid-gas heat exchanger 31 flows downward and, therefore, the circulation of air inside the indoor air unit 30 corresponds to natural phenomenon and does not proceed against the natural convection.

The process for manufacturing and installing the indirect outdoor air cooler 20 will be explained below.

In the example shown in FIG. 1, the outdoor air unit 40 and the indoor air unit 30 have substantially the same shape and dimensions of the housings thereof (therefore, the surface area for mounting on the wall is substantially the same), and the units are disposed and integrated to ensure substantially left-right symmetry with respect to the wall 1, thereby forming the indirect outdoor air cooler 20. The left-right direction as referred to herein relates to the figure.

When the units are installed, for example, first, a plurality of through holes is formed in the wall 1. Then, the outdoor air unit 40 and the indoor air unit 30 are disposed at positions such that the frames of the housings thereof sandwich the wall 1 in a left-right symmetrical configuration (in other words, the frames are disposed at substantially identical positions, with the wall 1 therebetween, as shown in FIG. 1), and the outdoor air unit 40 and the indoor air unit 30 are fixed with bolts and nuts through a plurality of through holes drilled in the wall 1 at the positions of the plurality of through holes. The pieces of piping 21 are then connected via separate through holes.

In the example shown in FIG. 1, the outdoor air unit 40 and the indoor air unit 30 are substantially identical in terms of not only the housings thereof, but also the internal configurations (substantially left-right symmetrical, as shown in the figure), and the difference therebetween is only in the presence of the circulating pump 22. Therefore, for example, the units configured to include no circulating pump 22 are manufactured at a plant, without distinguishing between the indoor air units and outdoor air units, and the manufactured unit can be used as either of the outdoor air unit 40 and the indoor air unit 30 during the installation. When the manufactured unit is used as the indoor air unit 30, the circulating pump 22 should be connected at the time of installation. However, with such an approach, the production efficiency at the plant rises and, therefore, a cost-reduction effect can be expected.

With the above-described indirect outdoor air cooler 20, the following effects are demonstrated.

Thus, in the indirect outdoor air cooler 20, the pair of liquid-gas heat exchangers 31 and 41 in which the internal fluid is liquid and the external fluid is gas is disposed inside and outside the building, respectively, with the wall 1 being interposed therebetween, the outdoor air is caused to flow as the external fluid of one liquid-gas heat exchanger 41, the indoor air is caused to flow as the external fluid of the other liquid-gas heat exchanger 31, and the internal fluids (liquids) of the two liquid-gas heat exchangers are circulated via the piping 21. As a result, heat exchange is performed between the outdoor air and the indoor air.

Because of the above-described feature, the indirect outdoor air cooler 20 demonstrates the following effects.

(1) Since the outdoor air unit 40 having the liquid-gas heat exchanger 41 with the outdoor air flowing therethrough and the indoor air unit 30 having the liquid-gas heat exchanger 31 with the indoor air flowing therethrough are disposed and integrated to be left-right symmetrical with respect to the wall 1 as a center, it is possible to use the units 30 and 40 that have frames of substantially the same structure and the production cost can be reduced.

(2) Further, since the outdoor air unit 40 and the indoor air unit 30 are fixed with bolts and nuts through a plurality of through holes drilled in the wall 1 at the positions of the plurality of through holes when the indirect outdoor air cooler 20 is installed, the installation cost can be reduced and the installation operations can be facilitated.

(3) The duct portion can be reduced in size and the pressure loss caused by duct resistance can be reduced by comparison with those of the conventional system shown in FIG. 14.

The air conditioning system (integrated air condition system) of the second embodiment will be explained below.

The air conditioning system of the second embodiment is also an indirect outdoor air cooling system, but has an integrated compact configuration.

In the indirect outdoor air cooling system of the first embodiment, a ductless compact configuration that is simple to install is suggested for the indirect outdoor air cooler 20, but the typical air conditioner 10 is substantially the same as in the conventional system.

In the second embodiment, an integrated indirect outdoor air cooling system is suggested in which the function of the indirect outer air cooler 20 and the function of the typical air conditioner 10 are integrated.

As a result, the entire device configuration can be simplified, the device can be reduced in size and cost, and the total power consumption can be also expected to reduce.

FIG. 2 shows the configuration of the air conditioning system (integrated air conditioning system) of the second embodiment.

FIG. 3 is a enlarged view of part of the configuration shown in FIG. 2.

In FIG. 2, the cooling object space to be cooled in the indirect outdoor air cooling system is assumed to be the same as in the example shown in FIGS. 1 and 14. Thus, the interior space that is the object of cooling is, for example, a server room having installed therein a large number of server racks 102 carrying heating elements 101 such as server devices (computer devices). The cold air is delivered into the under-floor space, the cold air is supplied via the under-floor space into the space of server setting, and the heating elements 101 are cooled by the cold air. As a result, the cold air becomes the warm air, and the warm air flows into the attic space.

The configuration for delivering the cold air into the under-floor space is an integrated indirect outdoor air cooling system 50 shown in the figure. The integrated indirect outdoor air cooling system 50 has the configuration in which the function of the indirect outdoor air cooler and the function of the typical air conditioner are integrated. In the indirect outdoor air cooling system 50, the warm air of the attic space is caused to flow in, the temperature of the warm air is initially decreased by the function of the indirect outdoor air cooler, and then the cold air of a predetermined temperature is generated by the function of the typical air conditioner. The integrated indirect outdoor air cooling system will be explained below in greater detail with reference to FIGS. 2 and 3.

The integrated indirect outdoor air cooling system 50 is constituted by an indoor air unit 60 and an outdoor air unit 70 shown in FIGS. 2 and 3.

When the indirect outdoor air cooler of the indirect outdoor air cooling system 50 functions, the heat exchange is performed while the outdoor air is separated from the indoor air, in the same manner as in the configuration of the conventional example shown in FIG. 14 or the configuration shown in FIG. 1. As a result, the outdoor moisture, dust, and corrosive gases contained in the outdoor air are not introduced into the interior space and, therefore, the reliability of electronic devices such as a server can be maintained.

The indoor air unit 60 and the outdoor air unit 70 are, for example, manufactured individually at respective plants and then installed so as to be in close contact with the surfaces of the wall 1, as shown in the figure. In this case, the integrated indirect outdoor air cooling system 50 is configured by additionally installing a piping 51 and a refrigerant piping 52 shown in the figure (or manufacturing them in sections, each being about half of the product, and connecting (by welding or the like) the sections together). Through holes should be provided in the wall 1 in order to install the piping 51 and the refrigerant piping 52, and those through holes are configured as shown in FIG. 1 or FIG. 14 and provided in four locations. The structure and installation of the indoor air unit 60 and the outdoor air unit 70 are substantially the same as those of the indoor air unit 30 and the outdoor air unit 40 of the first embodiment, and detailed explanation thereof is herein omitted.

The exterior side (outside the building) and the interior side (inside the building) are separated by the wall 1 as a boundary. The outdoor air unit 70 is installed on the exterior side, and the indoor air unit 60 is installed on the interior side. In other words, the outdoor air unit 70 is installed so as to be in close contact with the wall surface on the exterior side of the wall 1. The indoor air unit 60 is installed so as to be in close contact with the wall surface on the interior side of the wall 1.

The outdoor air unit 70 and the indoor air unit 60 are preferably provided at mutually corresponding positions, with the wall 1 being interposed therebetween. The mutually corresponding positions, with the wall 1 being interposed therebetween, as referred to herein, are, for example, the positions such as shown in FIG. 2 or FIG. 3. For example, when viewed from the outdoor air unit 70 side, the positions are such that the indoor air unit 60 is present on the rear side of the wall 1. In other words, assuming that the housing of the outdoor air unit 70 and the housing of the indoor air unit 60 have substantially the same shape and dimensions, as shown in the figure, the two housings are disposed so as to be in a substantially symmetrical relationship (substantially left-right symmetry) with respect to the wall 1, as shown in the figure. It goes without saying that the embodiment is not limited to this, and it is basically desirable that the units be installed in a manner such that facilitates the installation and shortens the piping.

The indoor air unit 60 has a stack 61. The stack 61 has an evaporator 61 a, a liquid-gas heat exchanger 61 b, and a fan 61 c and configured by stacking and integrating those components as shown in the figure. The configuration in which the evaporator, liquid-gas heat exchanger, and fan are thus integrated as a stack have significant merits, but the embodiment is not limited to this configuration. However, since the specific feature of the second embodiment is the “integrated” unit, it is necessary that the evaporator, liquid-gas heat exchanger, and fan be provided inside the indoor air unit 60:

Holes such as an indoor air inlet 62 and an indoor air outlet 63 shown in the figure are provided in the housing (for example, a box open at one side) of the indoor air unit 60. The fan 61 c produces the flow of air (shown by a dot-dash arrow in the figure) such that the warm air of the attic space flows from the indoor air inlet 62 into the unit 60 and passes through inside the indoor air unit 60 (in particular, inside the stack 61) and is then discharged from the indoor air outlet 63.

The stack 61 is configured such that the liquid-gas heat exchanger 61 b is provided on the upstream side of such air flow and the evaporator 61 a is provided on the downstream side. Therefore, the embodiment shown in the figure is not limited to this configuration and any configuration satisfying this condition can be used.

Further, even when a configuration other than stack (integrated) is used (such a configuration is not shown in the figures), it is necessary to provide a liquid-gas heat exchanger on the upstream side of air flow and provide an evaporator on the downstream side. In other words, a configuration is required in which the temperature of the indoor air (warm air) is so regulated that after the temperature has been reduced in the liquid-gas heat exchanger, the predetermined temperature (set temperature) is obtained in the evaporator.

The description above relates to the positional relationship of the liquid-gas heat exchanger 61 b and the evaporator 61 a, and the fan 61 c may be arranged at any position in the stack 61 (arrangement order with respect to the air flow). In other words, the fan 61 c may be at any of the most upstream position, most downstream position, or intermediate position (between the liquid-gas heat exchanger 61 b and the evaporator 61 a) of the air flow. The same is true for a configuration other than stack and substantially true for the below-described other stacks 71, 81, 91, 91′, 111, 121, and 121′.

The outdoor air unit 70 has the stack 71. The stack 71 has a condenser 71 a, a liquid-gas heat exchanger 71 b, and a fan 71 c, and configured by stacking and integrating those components as shown in the figure. Similarly to the indoor air unit 60, the configuration of the outdoor air unit is not limited to the stack. However, similarly to the indoor air unit 60, a condenser, a liquid-gas heat exchanger, and a fan should be provided inside the outdoor air unit 70.

Further, holes such as an outdoor air inlet 72 and an outdoor air outlet 73 shown in the figure are provided in the housing of the outdoor air unit 70. The fan 71 c creates an air flow (shown by a dot-dash arrow in the figure) such that the outdoor air flows from the outdoor air inlet 72 into the unit 70, passes through inside the outdoor air unit 70 (in particular, inside the stack 71), and flows out from the outdoor air outlet 73. The stack 71 is configured such that the liquid-gas heat exchanger 71 b is provided on the upstream side of this air flow, and the condenser 71 a is provided on the downstream side. Further, as has already been mentioned above, in this stack 71, the fan 71 c may be provided at any position (arrangement order with respect to the air flow), substantially in the same manner as in the stack 61 (therefore, a suitable arrangement is not limited to the example shown in the figure, and any configuration satisfying the abovementioned condition may be used). This is also true for a configuration other than the stack.

As mentioned hereinabove, the configurations of the indoor air unit 60 and the outdoor air unit 70 shown in FIGS. 2 and 3 are exemplary and not being limited to this. Substantially the same is true with respect to the configurations shown in FIG. 4 and subsequent figures.

The stacks 61 and 71 may have various configurations and may be manufactured by a variety of methods which are not explained in detail herein. However, the configuration that is easy to manufacture and/or compact and the production method thereof are preferred. For example, in the case of the stack 61, the evaporator 61 a, liquid-gas heat exchanger 61 b, and fan 61 c may be accommodated in respective housings (formed as units) and those housings may have substantially the same dimensions and shape. Further, for example, the housings may have a rectangular parallelepiped shape, and the stack 61 may be also provided with a substantially rectangular parallelepiped shape by stacking those three rectangular parallelepipeds.

In this example, the evaporator 61 a, liquid-gas heat exchanger 61 b, and fan 61 c are stacked and integrated (the stack 61 is formed), for example, by connecting the abovementioned housings to each other. The connection of the housings to each other may be performed, for example, by a typically used method, such as inserting a rod or bolt into the holes provided in the corners of the housings and tightening with nuts.

It goes without saying that a large number of holes for allowing the indoor air unit to pass therethrough and holes for passing various pipes are provided in the housings.

In this case, the liquid-gas heat exchangers 61 b and 71 b are connected to each other by the piping 51, substantially in the same manner as the liquid-gas heat exchangers 31 and 41 of the first embodiment, and the liquid (water or the like) located in the piping 51 is circulated inside the liquid-gas heat exchangers 61 b and 71 b and the piping 51 by the circulating pump 53. The liquid-gas heat exchangers 61 b and 71 b may have a well-known configuration and may be configured similarly to the liquid-gas heat exchangers 31 and 41; the configuration thereof is not explained in detail herein.

The liquid (water or the like) and the indoor air (warm air) pass through inside the liquid-gas heat exchanger 61 b. As a result, heat exchange is performed between the liquid (water the like) and warm air inside the liquid-gas heat exchanger 61 b and, essentially, the warm air is cooled (the heat of the warm air moves to the liquid) and the temperature of the warm air decreases. This, however, depends on the temperature of the outer air and warm air and does not guarantee that the temperature of the warm air drops. Where the temperature of the outdoor air is high, the circulating pump 53 can be stopped.

A refrigerant piping 52, an expansion valve 54, and a compressor 55 are provided in addition to the evaporator 61 a and condenser 71 a. The configuration of each component is substantially identical to that in the typical air conditioner 10. Thus, in a typical air conditioner 10, the evaporator 12 a and fan 12 b are provided in the air handling unit 12, and the evaporator 61 a is configured correspondingly to the evaporator 12 a. Further, as mentioned hereinabove, a compressor and a condenser (not shown in the figure) are provided in the refrigerator 11, and the compressor 55 and condenser 71 a are the components corresponding thereto. The expansion valve 54 is configured correspondingly to the expansion valve 13.

As shown in the figure, the evaporator 61 a, condenser 71 a, expansion valve 54, and compressor 55 are connected to the refrigerant piping 52. The refrigerant circulates in the evaporator 61 a, condenser 71 a, expansion valve 54, and compressor 55 via the refrigerant piping 52. Thus, the refrigerant circulates in the typical compression-type refrigeration cycle (vapor compression-type refrigeration cycle or the like): “evaporator 61 a→compressor 55→condenser 71 a→expansion valve 54→evaporator 61 a”. When the refrigerant is evaporated in the evaporator 61 a, the heat is drawn from the surroundings and the surroundings are cooled. This heat is radiated to the outdoor air in the condenser 71 a. The expansion valve 54 and the compressor 55 function in the conventional manner which is not explained in detail herein.

As shown in the figure, the expansion valve 54 is provided in the indoor air unit 60, but it may be also provided in the outdoor air unit 70. The compressor 55 is provided in the outdoor air unit 70, but it may be also provided in the indoor air unit 60. In other words, it is possible to use the configuration in which the expansion valve 54 is provided in the indoor air unit 60 and the compressor 55 is provided in the outdoor air unit 70, the configuration in which the expansion valve 54 is provided in the outdoor air 70 and the compressor 55 is provided in the indoor air unit 60, the configuration in which the expansion valve 54 and the compressor 55 are both provided in the indoor air unit 60, and the configuration in which the expansion valve 54 and the compressor 55 are both provided in the outdoor air unit 70.

In the example shown in the figure, the circulating pump 53 is provided in the indoor air unit 60, but it may be also provided in the outdoor air unit 70.

The liquid-gas heat exchanger 61 b and the liquid-gas heat exchanger 71 b are heat exchangers performing heat exchange between liquid and gas, but the embodiment is not limited to this example. Thus, heat exchangers performing heat exchange between gas and gas (will be referred to as gas-gas heat exchangers) may be provided instead of those liquid-gas heat exchangers. Obviously, in this case, some gas is used instead of the liquid.

Where a general term “fluid” is used to describe such liquids and gases, the liquid-gas heat exchangers and gas-gas heat exchangers may be generally referred to as fluid-gas heat exchangers or fluid-fluid heat exchangers. In this case, it can be said that a certain “fluid” flows in the piping 51. In other words, it can be said that any “fluid” can be circulated in two heat exchangers (the liquid-gas heat exchanger 61 b and the liquid-gas heat exchanger 71 b in the example shown in the figure, but the embodiment is not limited to this example, as mentioned hereinabove) via the piping 51. The same is substantially true for other below-described configurations. Thus, the liquid-gas heat exchangers may be replaced with gas-gas heat exchangers in the below-described configurations using the liquid-gas heat exchangers 81 b and 91 c and a piping 96, liquid-gas heat exchangers 111 b and 121 c and a piping 126, and liquid-gas heat exchangers 111 b and 171 c and a piping 162, and it may be said that some “fluid” is circulated.

Each component of the integrated indirect outdoor air cooling system 50 is explained above.

The operation of the integrated indirect outdoor air cooling system 50 of the above-described configuration will be explained below with reference to FIG. 3.

Thus, where the indoor air (warm air) of the attic space flows into the indoor air unit 60 via the indoor air unit inlet 62, first, the warm air passes through inside the liquid-gas heat exchanger 61 b, whereby heat exchange is performed between the warm air and the liquid (water or the like), and the temperature of the warm air decreases. The degree of this decrease depends on the temperature of the outdoor air (the temperature of the liquid) and the temperature of the warm air.

The warm air reduced in temperature then passes through the evaporator 61 a. As a result, the warm air reduced in temperature is cooled in the evaporator 61 a, assumes an even lower temperature and becomes cold air. The control is performed such that cold air assumes a predetermined temperature (set temperature). A controller 74 which is not depicted in the figure (shown only schematically in FIG. 3) is used for such control. The controller 74 controls the entire integrated indirect outdoor air cooling system 50 and also controls, for example, the revolution speed of the fans and the circulating pump 53, but such control is not explained herein. The controller 74 includes a computational device such as a CPU and a storage device such as a memory and executes a program that has been stored in advance in a memory or the like, thereby controlling the integrated indirect outdoor air cooling system by appropriately inputting the measured values from various sensors (not shown in the figure).

Further, the controller 74 may be provided inside the housing of the indoor air unit or inside the housing of the outdoor air unit, or outside those units (in the vicinity of the units). In FIG. 3, various signal wires relating to the controller 74 are not shown, but they are actually present and the controller 74 controls various components of the integrated indirect outdoor air cooling system 50 via the signal wires. For example, a temperature sensor (not shown in the figure) is provided in the vicinity of the blow port of the fan 61 c, and the controller 74 acquires the temperature measured by the temperature sensor via the signal wire (not shown in the figure). The controller 74 then controls the components relating to the above-mentioned typical compression-type refrigeration cycle via a signal wire (not shown in the figure) so that the measured temperature becomes the set temperature.

As described hereinabove, in the present example, the liquid-gas heat exchanger 61 b is disposed on the upstream side of the warm air flow, and the evaporator 61 a is disposed on the downstream side.

The cold air generated by the evaporator 61 a is discharged from the indoor air outlet 63 (after passing through the fan 61 c). In this case, as shown in FIG. 2, the indoor air unit outlet 63 is disposed to be connected to the under-floor space. Therefore, by contrast with the indirect outdoor air cooling system 20 shown in FIG. 1, the integrated indirect outdoor air cooling system 50 is disposed such that part thereof enters the under-floor space, as shown in FIG. 2. As a result, the cold air discharged from the indoor air outlet 63 flows into the under-floor space, flows into the space of server setting via the under-floor space and cools the heating elements 101. The cold air becomes warm air after cooling the heating elements 101, and this warm air flows into the attic space and then again flows from the indoor air unit inlet 62 into the indoor air unit 60.

Meanwhile, in the outdoor air unit 70, the outdoor air that has flown into the outdoor air unit 70 via the outdoor air inlet 72, first, passes through the liquid-gas heat exchanger 71 b, where heat exchange is performed between the outdoor air and liquid (water or the like). The liquid (water of the like), is heated by heat exchange with the warm air in the liquid-gas heat exchanger 61 b. The temperature of the liquid (water or the like) is reduced by heat exchange between the liquid (water or the like) that is thus increased in temperature and the outdoor air. The liquid (water or the like) reduced in temperature is supplied again by the circulating pump 53 and the piping 51 to the liquid-gas heat exchanger 61 b side.

Meanwhile, the temperature of the outdoor air is raised by the heat exchange with the liquid (water or the like) passing inside the liquid-gas heat exchanger 71 b. The outdoor air thus increased in temperature then passes through the condenser 71 a. The condenser 71 a further rises the temperature by radiating heat in the above-described manner. The heated outdoor air is then discharged from the outdoor air outlet 73.

The following effects mainly can be obtained with the above-described integrated indirect outdoor air cooling system 50.

(a) Compact Configuration

In the conventional configuration or the first embodiment, two devices, namely, the typical air conditioner and the indirect outdoor air cooler, are provided, but those two devices are integrated thereby making it possible to reduce the system. As a result, the installation space can be reduced and the system can be installed, for example, even when the machine room is narrow (alternatively, the system reduced in width to a degree unattainable in the conventional configuration can be installed).

(b) Reduction of Construction Cost Due to Ductless Configuration and Wall Mounting

The results are similar to those obtained in the above-described first embodiment, and it is not necessary to provide ducts as in the conventional configuration. The indoor air unit and outdoor air unit are manufactured in advance, for example, at a plant, and those units are mounted on the wall surface in the construction process (however, the operations of making holes for piping and hole for embedding the integrated outdoor-indoor air unit are still required), thereby making it possible to reduce the construction time and efforts and lower the construction cost.

(c) Size Reduction and Improvement of Manufacturability by Stacked Configuration

In the conventional configuration or the first embodiment, the evaporator, liquid-gas heat exchanger, and fan are present as separate units, for example in the configuration inside the building (those units are also manufactured individually). By contrast, in the second embodiment, the evaporator, liquid-gas heat exchanger, and fan are stacked and integrated to form a stack, thereby enabling size reduction. Further, since those units are manufactured together, rather than individually, the manufacturing process is facilitated. In particular, additional improvement of manufacturability can be expected by making those units substantially identical in shape and size, as shown in FIG. 2 or FIG. 3. The resultant configuration can be expected to be convenient in transportation and easy to install.

(d) Reduction in Blow Energy (Blow Power) and Cost Reduction by Using Shared Fans

In the configuration of the second embodiment, the number of fans can be reduced by comparison with that in the conventional configuration or the first embodiment and, therefore, the blow energy (blow power) and cost can be reduced. For example, in the configuration of the first embodiment shown in FIG. 1, a total of four fans, namely, the fan 11 a, fan 12 b, fan 32, and fan 42, are provided. By contrast, the configuration of the second embodiment shown in FIGS. 2 and 3 requires only two fans, namely, the fans 71 c. In other words, the number of fans can be reduced by half. Therefore, the purchasing cost of the fans can be reduced by half. Electric power is required to operate the fans, but this power is lower when two fans are used, than when tour fans are installed.

The air conditioning system of the third embodiment will be explained below.

The air conditioning system of the third embodiment resolves the above-described main problem. Thus, the air conditioning system is provided in which the outdoor air can be used for cooling the interior space even when the outdoor air temperature is high.

FIG. 4 shows the configuration of the air conditioning system (variation 1) of the third embodiment.

FIGS. 5A and 5B show the configuration of the air conditioning system (variation 2) of the third embodiment.

FIG. 6 shows the operation model of the air conditioning system of the third embodiment.

The air conditioning system of the third embodiment uses the outdoor air to cool the interior space, as in the above-described indirect outdoor air cooling system, and is therefore sometimes also called “outdoor-air-using air conditioning system”.

This system will be initially explained hereinabove with reference to FIG. 4.

The air conditioning system (variation 1) of the third embodiment shown in the figure is constituted by an outdoor air unit 80 provided outside the building and an indoor air unit 90 provided inside the building, with the wall 1 as a boundary, in the same manner as, for example, in the first and second embodiments. Such embodiment is, however, not limited to this example. For example, the below-described configuration shown in FIG. 10 may be also used.

In FIG. 4, the outdoor air unit 80 has a stack 81 and is also provided with part of a piping 96 where the second refrigerant is circulated. Specific examples of the second refrigerant include liquid such as “water” and Freon. The stack 81 has a liquid-gas heat exchanger 81 b, which is an example of the configuration for performing heat exchange between the second refrigerant and the outdoor air, and a fan 81 a. Those components are stacked and integrated as shown in the figure. The shape and structure of such a stack and manufacturing method thereof have already been explained in relation to the stacks 61 and 71 in the second embodiment, and the explanation thereof is herein omitted.

The liquid-gas heat exchanger 81 b and fan 81 a are not necessarily configured as a stack. Although they are shown in a simplified manner in FIG. 4, holes corresponding to the outdoor air inlet 72 and outdoor air outlet 73 are actually provided in the housing of the outdoor air unit 80, in the same manner as in the above-described outdoor air unit 70.

The installation location and installation method (including the manufacturing operations at the plant or the like) of the outdoor air unit 80 may be substantially the same as those of the outdoor air units 40 and 70, but such embodiment is not being limited to this. The same applies to the indoor air unit 90 shown in the figure. Thus, the housing of the indoor air unit 90 is also provided with holes (not shown in the figure) corresponding to the indoor air unit inlet 62 and indoor air unit outlet 63. The installation location and installation method (including the manufacturing operations at the plant or the like) of the indoor air unit 90 may be substantially the same as those of the outdoor air units 30 and 60, but the embodiment is not limited to this.

The indoor air unit 90 has the stack 91 and also has part of the piping 96 where the second refrigerant (for example, the cooling liquid such as “water”) circulates, the refrigerant piping 95 (in the figure, the entire refrigerant piping is shown, but only part thereof may be included) where the first refrigerant (for example, Freon) circulates, a pump 94 provided along the way in the piping 96, a compressor 92 and an expansion valve 93 provided along the way in the refrigerant piping 95. This is only an example, and the system is not limited to this example. For example, one, two or all of the pump 94, compressor 92, and expansion valve 93 may be provided at the outdoor air unit 80 side or outside the indoor air unit 90 (for example, inside the building). Where either of the compressor 92 or the expansion valve 93 is provided at the outdoor air unit 80 side, part of the refrigerant piping 95 is also installed at the outdoor air unit 80 side.

The above-mentioned stack 91 of the indoor air unit 90 has a fan 91 a, a condenser 91 b, a liquid-gas heat exchanger 91 c, which is an example of the configuration for performing heat exchange between the second refrigerant and the indoor air, and an evaporator 91 d and is configured by stacking and integrating those components as shown in the figure. It is not necessary that all of the fan 91 a, condenser 91 b, liquid-gas heat exchanger 91 c, and evaporator 91 d be stacked. For example, the fan 91 a may be provided separately. Alternatively, all of the components may be provided separately. However, as already explained in the second embodiment, the stacked configuration offers significant merits.

The mutual arrangement of the condenser 91 b, liquid-gas heat exchanger 91 c, and evaporator 91 d in the indoor air unit 90 is specified as described hereinbelow, regardless of whether or not the stacked configuration is used.

Thus, the components are arranged in the order of condenser 91 b→liquid-gas heat exchanger 91 c→evaporator 91 d from the upstream side of the flow of the air (indoor air) passing through in the indoor air unit 90. In other words, the condenser 91 b is disposed on the most upstream side of the air (indoor air) flow, the liquid-gas heat exchanger 91 c is disposed next thereto, and the evaporator 91 d is disposed on the most downstream side. In the case where the air (indoor air) flows as shown by a dot-dash arrow in the figure, the components are arranged in the order of condenser 91 b→liquid-gas heat exchanger 91 c→evaporator 91 d from the left side in the figure, for example, as shown in the figure.

By contrast, where the air flow formed by the fan 91 a is reversed, as shown in FIG. 8, the components are arranged in the order of evaporator 91 d→liquid-gas heat exchanger 91 c→condenser 91 b from the left side in the figure, as in a stack 91′ shown in FIG. 8. In other words, the components are arranged as condenser 91 b→liquid-gas heat exchanger 91 c-4 evaporator 91 d in the order of description from the upstream side of the air (indoor air) flow passing through in the indoor air unit 90, in the same manner as shown in FIG. 4. Even if the arrangement is changed, as shown in FIG. 8, the flow sequence of the first refrigerant does not change. Thus, the first refrigerant circulates in the following sequence: “evaporator 91 d→compressor 92→condenser 91 b→expansion valve 93→evaporator 91 d”.

In the case of the environment such as shown in FIG. 14, 1, or 2, it is desirable that the air flow in the same manner as in the indoor air unit 60 shown in FIGS. 2 and 3. In other words, it is desirable that the air flow as shown in FIG. 8, rather than as shown in FIG. 4 (it goes without saying, that the configuration in this case is such as shown in FIG. 8). The reason therefor has already been explained in the second embodiment.

Thus, for example, in FIG. 2, the outdoor air unit 80 and the indoor air unit 90 can be installed instead of the outdoor air unit 70 and the indoor air unit 60. In this case, as shown in FIG. 4, the cold air generated by the evaporator 91 d is delivered from the hole (not shown in the figure) on the upper side of the housing of the indoor air unit 90. However, as shown in FIG. 2, the destination of the cold air is the under-floor space on the lower side. Therefore, the configuration is preferred in which, as shown in FIG. 8, the cold air generated by the evaporator 91 d is delivered from the hole (not shown in the figure) on the lower side of the housing of the indoor air unit 90. The reasons therefor are also associated with the inflow of the return air (warm air) from the attic space (they have already been explained and are omitted herein).

The explanation now returns to FIG. 4.

As shown in the figure, the evaporator 91 d, condenser 91 b, expansion valve 93, and compressor 92 are connected to the refrigerant piping 95. The first refrigerant circulates in the evaporator 91 d, condenser 91 b, expansion valve 93, and compressor 92 via the refrigerant piping 95. Thus, the first refrigerant circulates in the following typical compression-type refrigeration cycle (vapor compression-type refrigeration cycle or the like): “evaporator 91 d compressor 92→condenser 91 b→expansion valve 93→evaporator 91 d”. As in the conventional configuration, when the first refrigerant is evaporated in the evaporator 91 d, the heat is drawn from the surroundings, and the surroundings (indoor air) are thus cooled. The heat that has been drawn in is radiated to the surroundings in the condenser 91 b. The expansion valve 93 and the compressor 92 function in the same manner as in the conventional configuration and are not explained herein.

As shown in FIG. 14, 1, 2, or 3, the condenser is usually disposed on the exterior side (outside the building) and radiates the heat to the outdoor air. Meanwhile, as shown in FIG. 4, in the third embodiment, the condenser is provided on the interior side (for example, inside the indoor air unit 90, but the embodiment is not limited to this arrangement). This is one of the specific features of the third embodiment. It will be explained hereinbelow in greater detail.

As mentioned hereinabove, the indoor air serving as the return air (warm air) flowing from the interior space (the attic space) into the indoor air unit 90, first, passes through the condenser 91 b, then passes through the liquid-gas heat exchanger 91 c, and finally passes through the evaporator 91 d. When passing through the condenser 91 b, the return air is heated by the heat radiated from the condenser 91 b, and when the return air then passes through the liquid-gas heat exchanger 91 c, the temperature thereof drops due to heat exchange with the second refrigerant (water or the like). The return air then passes through the evaporator 91 d where it is cooled and becomes cold air. The cold air is supplied, for example, through the under-floor space, for example, into the server room which the object of cooling.

In this configuration, the liquid-gas heat exchanger 81 b and the liquid-gas heat exchanger 91 c are substantially the same as the liquid-gas heat exchangers 61 b and 71 b of the second embodiment and connected to each other by the piping 96. The second refrigerant (water or the like) provided inside the piping 96 is circulated by the pump 94 inside the liquid-gas heat exchangers 81 b and 91 c and the piping 96. Further, the liquid-gas heat exchangers 81 b and 91 c may be considered substantially identical to the liquid-gas heat exchangers 31 and 41 or the liquid-gas heat exchangers 61 b and 71 b.

The second refrigerant (water or the like) passes through in the liquid-gas heat exchanger 91 c, and the indoor air (warm air) also passes therethrough. As a result, heat exchange is performed between the second refrigerant (water or the like) and warm air inside the liquid-gas heat exchanger 91 c and, essentially, the warm air is cooled (the heat of the warm air moves to the liquid) and the temperature of the warm air decreases. In the conventional configuration, this, however, depends on the temperature of the outer air and warm air and does not guarantee that the temperature of the warm air drops.

However, in the configuration of the third embodiment shown in FIG. 4, the temperature of the indoor air (warm air) rises since the radiation of heat by the condenser 91 b takes place before (on the upstream side of) the liquid-gas heat exchanger 91 c. For example, even if the temperature of the return air (warm air) from the interior space is 30° C. and the outdoor air temperature is 35° C., where the temperature of the indoor air that has passed through the condenser 91 b becomes 45° C., the temperature of the indoor air decreases in the liquid-gas heat exchanger 91 c (for example, 45° C.→36° C.)

In other words, with the conventional configuration, even in the environment in which the outdoor-air-using cooling (indirect outdoor air cooling) is functionally imperfect, the cooling still functions. Further, the cooling efficiency of the indoor air increases with the increase in the difference in temperature between the indoor air and outdoor air.

In the configuration described herein, for example, the indoor air cooling can be substantially performed by the outdoor air even in the environment with a high outdoor air temperature, and 36° C. is higher than the natural indoor air temperature (30° C.). However, the cooling of the first refrigerant in the condenser 91 b uses the outdoor air with a temperature of 35° C. in the conventional configuration, but uses the indoor air with a temperature of 30° C. in the present example. In other words, where the outdoor air temperature is higher than the temperature of the return air (indoor air), the configuration of the third embodiment shown in FIG. 4 demonstrates a higher effect of cooling the first refrigerant in the condenser 91 b than the conventional configuration.

As a result, where the outdoor air temperature is so high, power consumption is reduced (energy saving effect is high) by comparison with the conventional configuration, as demonstrated by simulation below. This will be described below in greater detail.

The configuration shown in FIG. 4 or in the below-described FIG. 8 has the following merits, for example, over that shown in FIG. 3.

Thus, in the configuration shown in FIGS. 4 and 8, the condenser is installed on the interior side (indoor air unit). The resultant merits are that there are locations where the piping length is reduced (the piping 96 is shorter than the refrigerant piping 52) and the number of through holes in the wall 1 is reduced (“4”→“2”). Another merit of the configuration shown in FIGS. 4 and 8 over those shown in the below-described FIGS. 5A, 5B, 9, 11, and 12 is that the number of through holes in the wall 1 can be reduced (“5”→“2”).

The configuration example of the air conditioning system (variation 2) of the third embodiment will be explained below with reference to FIGS. 5A and 5B. FIG. 5A shows the first example, and FIG. 5B shows the second example.

The configurations shown in FIGS. 5A and 5B are based on the configuration shown in FIG. 4. In those configurations, a compressor is provided also on the outdoor air unit side and the switching control is performed by using a three-way valve 112 (switching device shown in the figure). As a result, operations substantially similar to those of second embodiment (FIG. 3) can be also performed.

The space which is the object of cooling with the air conditioning system (variation 1) (variation 2) shown in FIGS. 4, 5A, and 5B is assumed, for example, to be the same as in FIG. 1 or 2. Thus, the interior space that is the object of cooling is, for example, the server room having installed therein a large number of server racks 102 carrying heating elements 101 such as server devices (computer devices). The cold air is delivered into the under-floor space, the cold air is supplied into the space of server setting, and the heating elements 101 are cooled by the cold air. As a result, the cold air becomes warm air, and the warm air flows into the attic space. The return air (warm air) from the attic space flows into the indoor air unit 90 shown in FIG. 4 or an indoor air unit 120 shown in FIGS. 5A and 5B, and the cold air is generated in those indoor air units and delivered into the under-floor space.

First, the configuration shown in FIG. 5A will be explained below.

The air conditioning system (variation 2) of the third embodiment shown in FIG. 5A is constituted by the indoor air unit 120 and an outdoor air unit 110. The housings, manufacture/installation methods, and mutual arrangements of the indoor and outdoor air units for the indoor air unit 120 and the outdoor air unit 110 may be substantially the same as for the indoor air unit 60 and the outdoor air unit 70 and are not explained in detail herein.

Initially, the indoor air unit 120 will be explained below.

The indoor air unit 120 has the stack 121. This stack 121 has a fan 121 a, a condenser 121 b, a liquid-gas heat exchanger 121 c, and an evaporator 121 d and configured by stacking the integrating those components as shown in the figure.

The stack 121 is identical to the stack 91 shown in FIG. 4. Therefore, the conditions same as those of the stack 91 are applied. Thus, the components are disposed as condenser 121 b→liquid-gas heat exchanger 121 c→evaporator 121 d in the order of description from the upstream side of the flow of air (indoor air) passing through in the indoor air unit 120.

In the configuration in which the evaporator, liquid-gas heat exchanger, condenser, and fan are integrated as a stack in the above-described manner, significant merits such as described hereinabove can be obtained, but the embodiment is not limited to such configuration. For example, only any two or more of those four structural components may be stacked, or all four structural components may be provided separately (however, in this case, the components are also arranged as condenser→liquid-gas heat exchanger→evaporator in the order of description from the upstream side of the indoor air flow, as explained with reference to FIG. 4).

In the third embodiment, holes such as an indoor air inlet 128 and an indoor air outlet 127 shown in the figure are provided in the housing of the indoor air unit 120, in the same manner as in the second embodiment (those holes are not shown in FIG. 4). In the present example, a fan 121 a forms the air flow shown by a one-dot-dash arrow in the figure. Thus, the fan 121 a creates the air flow (shown by a one-dot-dash arrow in the figure) such that the warm air of the attic space flows from the indoor air inlet 128 into the indoor air unit 120, passes through in the indoor air unit 120 (in particular, the stack 121), and becomes cold air which is discharged from the indoor air outlet 127. The cold air discharged from the indoor air outlet 127 flows into the server room through the under-floor space.

The fan 121 a may also form the air flow (the flow in the direction opposite to that of the flow shown by the one-dot-dash arrow in the figure) such that the hole serving as the indoor air outlet 127 in the figure is the indoor air inlet and the hole serving as the indoor air inlet 128 in the figure is the indoor air outlet, in the same manner as shown in FIGS. 2 and 3. Such configuration example is shown in FIG. 9. As shown in FIG. 9, an indoor air inlet 127′ is provided on the upper side of the housing, and the indoor air outlet 128′ is provided at the lower side of the housing.

Further, in this case, the configuration of the stack 121 is changed as shown in FIG. 9. Thus, as described hereinabove, the components are arranged as condenser→liquid-gas heat exchanger→evaporator in the order of description from the upstream side of the flow of air (indoor air) inside the indoor air unit. Therefore, the condenser 121 h and the evaporator 121 d shown in FIG. 5A are exchanged one for another. Thus, the stack 121′ shown in FIG. 9 is configured.

As shown in the figure, in the stack 121′, the condenser 121 b, liquid-gas heat exchanger 121 c, and evaporator 121 d are disposed in the order of description from the right side in the figure. The indoor air flow formed by the fan 121 a is such that the indoor air flows into the housing from the indoor air inlet 127′ and is discharged from the indoor air outlet 128′ as shown by a one-dot-dash arrow in FIG. 9. Therefore, the components are arranged as condenser 121 b→liquid-gas heat exchanger 121 c→evaporator 121 d in the order of description from the upstream side of such air flow.

The explanation now returns to FIG. 5A.

The outdoor air unit 110 has the stack 111.

The stack 111 has a fan 111 a, a liquid-gas heat exchanger 111 b, and a condenser 111 c and is configured by stacking and integrating those components as shown in the figure. It is not necessary that those three structural components be all stacked. The housing of the outdoor air unit 110 (similarly to the outdoor air unit 70) is provided with holes such as an outdoor air inlet 114 and an outdoor air outlet 115, which are shown in a simplified manner in FIG. 4. The fan 111 a creates the air flow (shown by a dot-dash line in the figure) such that the exterior air (outdoor air) flows from the outdoor air inlet 114 into the outdoor air unit 110, passes through the stack 111, and is then discharged from the outdoor air outlet 115.

The stack 111 may by itself be identical to the stack 71. Similarly to the stack 71, the stack 111 is configured to be provided with the liquid-gas heat exchanger 111 b on the upstream side of the air flow (shown by a dot-dash arrow in the figure) such as explained hereinabove, and with the condenser 111 c on the downstream side. The same configuration is used in the case where no stack is configured.

An expansion valve 123 and a compressor 113 are each provided in either of the outdoor air unit 110 and the indoor air unit 120. In the example shown in the figure, the expansion valve 123 is provided in the indoor air unit 120, and the compressor 113 is provided in the outdoor air unit 110, but the embodiment is not limited to this example (the modification has already been explained in the second embodiment, and the explanation thereof is herein omitted).

Further, as shown in the figure, the evaporator 121 d, expansion valve 123, and compressor 113 are connected to a refrigerant piping 125. In addition a three-way valve 112, which is an example of a switching device, is provided in the refrigerant piping 125 along the way thereof, and the refrigerant piping is branched from the three-way valve 112 into a refrigerant piping 125 a and a refrigerant piping 125 b, which are shown in the figure. The refrigerant piping 125 a is connected to the condenser 121 b of the stack 121. The refrigerant piping 125 b is connected to the condenser 111 c of the stack 111 and merges at the distal end thereof with the refrigerant piping 125 a. As a result, by performing valve opening/closing switching of the three-way valve 112, it is possible to cause the first refrigerant to flow in either of the refrigerant piping 125 a and the refrigerant piping 125 b. In other words, the first refrigerant can flow into either of the condenser 111 c and the condenser 121 b.

Thus, the first refrigerant circulates in the evaporator 121 d, condenser 111 c or condenser 121 b, expansion valve 123, and compressor 113 through the refrigerant piping 125 (including the refrigerant piping 125 a and the refrigerant piping 125 b). Thus, the first refrigerant circulates in the following typical compression-type refrigeration cycle (vapor compression-type refrigeration cycle or the like): “evaporator 121 d→compressor 113→condenser 111 c or condenser 121 b→expansion valve 123→evaporator 121 d”.

In the same manner as in the conventional configuration, when the first refrigerant is evaporated in the evaporator 121 d, the heat is drawn from the surroundings, and the surroundings are thereby cooled. The heat that has been drawn in is radiated into the surroundings in the condenser 111 c or the condenser 121 b. The expansion valve 123 and the compressor 113 also function in the same manner as in the conventional configuration and the explanation thereof is herein omitted.

The refrigerant switching control performed by the three-way valve 112 is determined, for example, by the outdoor air temperature or indoor air temperature. Alternatively, the control may be determined on the basis of the amount of consumed power.

Thus, the effect demonstrated by the configuration shown in FIG. 4 is greatly superior to that of the conventional air conditioning system, in particular when the outdoor air temperature is high (for example, equal to or higher than 30° C.), but when the outdoor air temperature is low, the reverse effect can sometimes be obtained.

Accordingly, for example, the controller 130 shown in the figure performs the valve opening/closing control of the three-way valve 112 and causes the first refrigerant to flow into the refrigerant piping 125 a (condenser 121 b), for example, when the outdoor air temperature is equal to or higher than a predetermined temperature, or when “outdoor air temperature>indoor air temperature” and the difference in temperature between the outdoor air and the indoor air is equal to or greater than a predetermined value. The effect produced by the operation in this case is substantially the same as that illustrated by FIG. 4. Thus, where a state is assumed in which the first refrigerant flows into the piping 125 a (condenser 121 b), the heat is radiated from the condenser 121 b into the indoor air and, therefore, the stack 121 functions in a substantially the same manner as the stack 91 (the indoor air temperature, as referred to herein, is the temperature of the return air from the attic space).

Thus, the return air (warm air) flowing from the interior space (the attic space thereof) into the indoor air unit 120 via the indoor air inlet 128 initially passes through the condenser 121 b, then passes through the liquid-gas heat exchanger 121 c, and finally passes through the evaporator 121 d. When the return air passes through the condenser 121 b, the temperature of the return air rises due to heat radiation from the condenser 121 b. When the return air thereafter passes through the liquid-gas heat exchanger 121 c, the temperature of the return air is decreased by heat exchange with the second refrigerant (water or the like). When the return air eventually passes through the evaporator 121 d, the return air is cooled and becomes cold air.

It is possible to measure the amount of consumed power before and after performing the valve opening/closing control of the three-way valve 112, allow the system to stay as is if the amount of consumed powder has reduced and again perform the valve opening/closing control of the three-way valve 112 and return to the original state (the state in which the first refrigerant flows into the refrigerant piping 125 b (condenser 111 c)) if the amount of consumed powder has increased. Alternatively, it is possible to perform the valve opening/closing control of the three-way valve 112 and return to the original state (the state in which the first refrigerant flows into the refrigerant piping 125 b (condenser 111 c)) when, for example, the outdoor air temperature became less than a predetermined temperature after the switching, or when “outdoor air temperature≦indoor air temperature” or “outdoor air temperature>indoor air temperature”, but the difference in temperature between the outdoor air and indoor air is less than a predetermined value.

For example, when the outdoor air temperature is less than a predetermined temperature, the first refrigerant is caused to flow into the refrigerant piping 125 b (condenser 111 c) by performing the valve opening/closing control of the three-way valve 112. The operations in this case are the same as illustrated by FIGS. 2 and 3.

Thus, the return air (warm air) flowing from the interior space (the attic space thereof) through the indoor air inlet 128 into the indoor air unit 120 passes, without any particular changes, through the condenser 121 b. The temperature of the return air decreases due to heat exchange with the second refrigerant (water or the like) when the return air then passes through the liquid-gas heat exchanger 121 c, and finally the return air is cooled when passing through the evaporator 121 d and becomes cold air. Meanwhile, the heat drawn from the surroundings by the evaporator 121 d is radiated to the outdoor air in the condenser 111 c. The second refrigerant is circulated by the circulating pump 124 inside the piping 126. The piping 126 is connected to the liquid-gas heat exchangers 111 b and 121 c in the same manner as the piping 51.

Such valve opening/closing control of the three-way valve 112 is performed, for example, by the controller 130 shown in the figure, but the detailed explanation thereof is herein omitted. The controller 130 is a control device of the entire present air conditioning system that has a CPU/MPU and a memory and performs the control of adjusting the temperature of the cold air, for example, by inputting temperature data from a temperature sensor (not shown in the figure). The controller 130 may be installed at any location.

In the example shown in FIG. 5A, check valves 122 a and 122 b are provided, as shown in the figure, in order to prevent the first refrigerant that has flown into the refrigerant piping 125 a from flowing into the refrigerant piping 125 b (and, conversely, to prevent the first refrigerant that has flown into the refrigerant piping 125 b from flowing into the refrigerant piping 125 a). Thus, as shown in the figure, the refrigerant piping 125 a and the refrigerant piping 125 b, which are the branched pieces of the refrigerant piping 125, merge in a merging point R shown in the figure and again become a single refrigerant piping 125. In the refrigerant piping 125 a, as shown in the figure, the check valve 122 a is provided before the merging point R. In the refrigerant piping 125 b, the check valve 122 b is likewise provided before the merging point R.

The configuration shown in FIG. 4 will be explained below using FIG. 5A. Since the condenser 111 c is not present, the three-way valve 112, refrigerant piping 125 b, and check valves 122 a and 122 b are also not present (the refrigerant piping 125 a can be considered as the refrigerant piping 125).

Conversely, where the configuration shown in FIG. 5A is explained on the basis of the configuration shown in FIG. 4, initially, the condenser 111 c is added, the refrigerant piping 125 is branched along the way, and the refrigerant piping 125 b, which is obtained as a branched piping, is connected to the condenser 111 c. Then, the three-way valve 112, which is an example of a switching device, is provided in the branching point of the refrigerant piping 125, and the first refrigerant is caused by the switching device to flow in either of the condenser 121 b and the condenser 111 c. The abovementioned check valves 122 a and 122 b are then also added.

The configuration example shown in FIG. 5B will be explained below.

The configuration shown in FIG. 5B is substantially identical to the configuration shown in FIG. 5A and only partially different therefrom. Accordingly, only those features by which the configuration shown in FIG. 5B differs from that shown in FIG. 5A will be explained below, and the explanation of the configuration substantially identical to that shown in FIG. 5A will be omitted.

In the configuration shown in FIG. 5B, a three-way valve 112′ shown in the figure is provided instead of the three-way valve 112 shown in FIG. 5A. The three-way valve 112 shown in FIG. 5A is provided before (inflow side) the condenser 111 c. In contrast, the three-way valve 112′ shown in FIG. 5B is provided after (outflow side) the condenser 111 c. The refrigerant piping 125 branches into the refrigerant piping 125 a and the refrigerant piping 125 b form the three-way valve 112′ in a substantially the same manner as shown in FIG. 5A. The refrigerant piping 125 b is connected to the expansion valve 123, and the refrigerant piping 125 a is connected to the condenser 121 b in a substantially the same manner as shown in FIG. 5A.

In the configuration shown in FIG. 5A, the refrigerant is caused to flow in either of the condenser 111 c and the condenser 121 b by the valve switching control of the three-way valve 112. In contrast, in the configuration shown in FIG. 5B, the refrigerant necessarily flows in the condenser 111 c, and whether or not to cause the refrigerant to flow in the condenser 121 b is controlled by switching the three-way valve 112′.

Since the temperature of the refrigerant at the outlet side of the compressor 113 is usually higher than the outdoor air temperature, the refrigerant temperature can be expected to be decreased by using the configuration in which the refrigerant necessarily flows in the condenser 111 c. Further, when “outdoor air temperature>indoor air temperature”, the refrigerant is caused to flow in the refrigerant piping 125 a (the refrigerant is also caused to flow in the condenser 121 b) by performing the switching control of the three-way valve 112′. As a result, the refrigerant temperature can be temporarily decreases in the condenser 111 c and then further lowered close to the indoor air temperature in the condenser 121 b.

The outdoor air temperature has the same meaning as the temperature of the outdoor air.

With the configuration shown in FIG. 5B, the amount of heat exchange between the refrigerant and the indoor air in the condenser 121 b is decreased. Therefore, the condenser 121 b can be reduced in size. Further, since the amount of heat that should be taken out by the heat exchanger 121 c is reduced, the efficiency can be expected to increase (for example, the blow amount of the fan 111 a is decreased or the flow rate of the refrigerant circulated by the pump 124 is reduced).

The configuration shown in FIG. 5B can be also explained in the following manner.

Thus, the outdoor air unit 110 is also provided with the condenser 111 c, the refrigerant piping 125 is connected to the condenser 111 c, the refrigerant piping 125 is branched at the refrigerant outlet side of the condenser 111 c, and a switching device (three-way valve 112′) is provided in the branching point. The switching device switches the circulation to either one of the first route in which the first refrigerant is circulated in the condenser 121 b inside the indoor air unit 120 and then circulated in the expansion valve 123 and the second route in which the first refrigerant is circulated in the expansion valve 123, without circulating in the condenser 121 b inside the indoor air unit 120. The outer switching control performed by the switching device is executed, for example, by the controller 130.

FIG. 6 shows the operation model of the air conditioning system of the third embodiment and the simulation results.

First, the simulation operation model shown in FIG. 6A will be explained.

The explanation below relates to the configuration shown in FIG. 4, but the same applies to the configurations shown in FIGS. 5A and 5B (when they are operated in the same manner as the configuration shown in FIG. 4).

In FIG. 6, a thick-line arrow shows the flow of air (indoor air). The components arranged along the flow of air (indoor air), that is, the components through which the indoor air flows, include a heating element 140, a condenser 141, a liquid-gas heat exchanger 142, and an evaporator 143 shown in the figure.

The heating element 140 corresponds to the abovementioned heating element 101 (server device or the like) located in the interior space of the cooling object. The condenser 141 corresponds to the condenser 91 b, the liquid-gas heat exchanger 142 corresponds to the liquid-gas heat exchanger 91 c inside the indoor air unit 90, and the evaporator 143 corresponds to the evaporator 91 d. The compressor 144 shown in the figure corresponds to the compressor 92, and the expansion valve 145 shown in the figure corresponds to the expansion valve 93.

The thin-line arrows shown in the figure and connecting those condenser 141, evaporator 143, compressor 144, and expansion valve 145 show the flow of the first refrigerant. Thus, the first refrigerant circulates in the following compression-type refrigeration cycle (vapor compression-type refrigeration cycle or the like): “evaporator 143→compressor 144→condenser 141→expansion valve 145→evaporator 143”.

The pump 146 shown in the figure corresponds to the pump 94, and the liquid-gas heat exchanger 147 shown in the figure corresponds to the liquid-gas heat exchanger 81 b on the outdoor air unit 80 side. The thin-line arrows shown in the figure and connecting those pump 116, liquid-gas heat exchanger 147, and liquid-gas heat exchanger 142 show the flow of the second refrigerant (water or the like). As a result, in the liquid-gas heat exchanger 142, the second refrigerant exchanges heat with the indoor air, whereas in the liquid-gas heat exchanger 147, the second refrigerant exchanges heat with the outdoor air. Therefore, when the outdoor air temperature is low, an indirect outdoor air cooling function is realized such that the indoor air is indirectly cooled by the outdoor air through the second refrigerant.

FIG. 6A shows an example of the temperatures of the indoor air and the first refrigerant at each stage of the abovementioned cycle. This is obviously only one example. Further, this example shows the temperatures that are ideal for simulation and does not reflect actual results. For example, although the temperature of the first refrigerant drops significantly in the condenser 141, it does not decrease to reach the temperature (32° C.) equal to the indoor air temperature, as shown in the figure, and has a somewhat higher value (33° C.)

The explanation is started with the evaporator 143. In the example shown in the figure, the indoor air is cooled in the evaporator 143 and becomes cold air with a temperature of 18° C. The heating element 140, which is a server device or the like, is cooled by the cold air, and the indoor air becomes warm air with a temperature of 32° C. The warm air with a temperature of 32° C. passes through the condenser 141.

The first refrigerant with a high temperature (66° C.) that is generated by the compressor 144 flows into the condenser 141, and the heat thereof is radiated to the surroundings. In the condenser 141, the first refrigerant with a high temperature (66° C.) is cooled by the warm air with a temperature of 32° C. As a result, after the condenser 141, the temperature of the first refrigerant decreases to 32° C., but the temperature of the warm air (indoor air) rises to 55° C.

The first refrigerant with a temperature of 32° C. becomes the first refrigerant with a temperature of 10° C. in the expansion valve 145 of the next stage and flows into the evaporator 143. As a result, the evaporator 143 cools the indoor air in the above-described manner and generates cold air with a temperature of 18° C.

Meanwhile, the warm air with a temperature of 55° C. undergoes heat exchange with the second refrigerant when passing through the liquid-gas heat exchanger 142. As a result, the temperature of this warm air drops to 36° C. The warm air with a temperature of 36° C. passes through the evaporator 143 and becomes cold air with a temperature of 18° C. as described hereinabove.

As described hereinabove, the return air from the interior space has a temperature of 32° C., whereas the warm air flowing into the evaporator 143 has a temperature of 36° C. Thus, although the indirect outdoor air cooling function is used, the temperature, conversely, rises.

However, with the indirect outdoor air cooling function, the warm air with a temperature of 55° C. is cooled to become warm air with a temperature of 36° C., and the cooling function is served. Furthermore, since the difference in the temperature is large, the efficiency of cooling the warm air (indoor air) is superior. This is because even in a state with a very high outdoor air temperature (for example, 36° C.), the warm air temperature is much lower than 55° C. Where the warm air passing through the liquid-gas heat exchanger 142 becomes the return air with a temperature of 32° C., when the outdoor air temperature is 36° C., the temperature of the return air does not decrease, or it is even possible that this temperature will increase. Meanwhile, in the third embodiment, it is highly probable that the indirect outdoor air cooling will function even when the outdoor air temperature is very high.

In this case, the indoor air assumes a high temperature of 55° C., as mentioned hereinabove, because the condenser 141 is provided on the indoor air unit side (interior side) and the indoor air is caused to pass therethrough. As shown in FIG. 14 and FIGS. 1 to 3, the condenser is usually provided on the exterior side to radiate heat to the outdoor air. With such a configuration, no problem is encountered when the outdoor air temperature is low, and the first refrigerant is sufficiently cooled by the outdoor air in the condenser.

However, in a state with a very high outdoor air temperature (for example, 36° C.), the first refrigerant is not sufficiently cooled by the outdoor air in the condenser, and where the room temperature is to be maintained at a set value in this case, power consumption rises. By contrast, in the air conditioning system of the third embodiment, the first refrigerant is cooled in the condenser 141, as mentioned hereinabove, by the indoor air with a temperature of 32° C. that is lower than the outdoor air temperature. As a result, the temperature of the first refrigerant can be reduced with respect to that of the outdoor air and power consumption is decreased.

FIG. 6B shows the simulation results relating to the reduction in power consumption.

In the graph shown in FIG. 6B, the outdoor air temperature (° C.) is plotted against the abscissa, and the consumed power (kW) is plotted against the ordinate.

Data represented by triangles (Δ) in the graph indicate the power consumed by the indirect outdoor air cooling function (mainly the power consumed by the fans and the pump 146), data represented by rhombs (⋄) indicate the power consumed by the refrigeration cycle (mainly the power consumed by the compressor 144), and data represented by circles (∘) indicate the total power consumption (power consumption of the entire system). Among those symbols, the hollow ones (hollow triangles Δ, hollow rhombs ⋄, and hollow circles ∘) represent data corresponding to the conventional air conditioning system, and the full ones (full triangles ▴, full rhombs ♦, and full circles ) represent data corresponding to the air conditioning system of the third embodiment. The conventional air conditioning system is, for example, the air conditioning system shown in FIG. 14, but the embodiment is not limited to this, and it may also be the air conditioning system of the first embodiment or the second embodiment.

As shown in the figure, where the outdoor air temperature is comparatively low, the total power consumption of the conventional air conditioning system is not substantially different from that of the present air conditioning system (air conditioning system of the third embodiment).

However, where the outdoor air temperature becomes higher than a certain level (for example, a level of above 30° C. can be selected as a criterion), the indirect outdoor air cooling essentially does not function in the conventional air conditioning system and, therefore, the fans and the pump 146 are stopped, thereby reducing to zero the power consumption (hollow triangles Δ) relating to the indirect outdoor air cooling function, as shown in the figure. Meanwhile, in the present air conditioning system, since the indoor air is at a very high temperature (55° C. or the like) as mentioned hereinabove, even when the outdoor air temperature exceeds 30° C., and even when it then exceeds 35° C., the indirect outdoor air cooling functions, the fans and the pump 146 are not stopped and power consumption is at a constant level (full triangles ▴), as shown in the figure.

In the conventional air conditioning system, in the range of outdoor air temperature (referred to hereinbelow as a high-temperature range) in which the power consumption (hollow triangles ▴) relating to the indirect outdoor air cooling is zero, the total power consumption increases rapidly with the increase in temperature, as shown in the figure. In such a high-temperature range, in the conventional air conditioning system, the condition of “total power consumption (hollow circles ∘)=power consumption of refrigeration cycle (hollow rhombs ⋄)” is valid. In other words, in the high-temperature range, since the power consumption of the refrigeration cycle (hollow rhombs ⋄) increases rapidly, the total power consumption also increases rapidly.

Meanwhile, in the present air conditioning system, even in the high-temperature range, the power consumption of the refrigeration cycle (full rhombs ♦) increases gradually with the increase in outdoor air temperature, in a substantially the same manner as at a lower temperature and does not increase rapidly. For this reason, in the high-temperature range, as shown in the figure, the difference in total power consumption between the conventional air conditioning system and the present air conditioning system increases as the outdoor air temperature rises.

Thus, under the environment in which the outdoor air temperature is higher than a certain level, the power consumption of the air conditioning system of the third embodiment is lower than that of the conventional air conditioning system, and the energy saving effect increases with the increase in outdoor air temperature.

Under the environment with a low outdoor air temperature, the air conditioning system of the third embodiment can demonstrate a reverse effect in terms of energy saving. Therefore, the air conditioning system (variation 1) of the third embodiment shown in FIG. 4 essentially can be switched at any time to the conventional air conditioning system by using the configuration shown in FIG. 5A. This, however, depends on the installation environment, and, for example, where the installation location is in a hot climate zone, even the configuration shown in FIG. 4 can be used without any problem.

Where the degree of cooling of the first refrigerant is high (the refrigerant temperature is low; the degree of overcooling is high), the refrigeration effect and refrigeration capacity increase. This is a well-known matter, as described, for example, in the reference document (Japanese Patent Application Publication No. 2010-7975, in particular, paragraphs [0009] and [0038] thereof). In the above-mentioned reference document, it is indicated that, for example, where the overcooling degree of the first refrigerant decreases, the refrigeration effect (the relative variation amount of enthalpy of the refrigerant in the evaporator) decreases and, therefore, the refrigeration capacity decreases even if the refrigerant circulation amount is the same.

Meanwhile the temperature of the server room, which is the cooling object space, should be maintained substantially at a set temperature, and in the example shown in FIG. 6A, the evaporator should continuously generate cold air with a temperature of about 18° C. Even when the overcooling degree of the refrigerant decreases, it is necessary, for example, to increase the refrigerant circulation amount in order to generate cold air with a temperature of about 18° C., and power consumption, therefore, increases. In the present air conditioning system, under the environment with a high outdoor air temperature, the overcooling degree of the first refrigerant does not become lower than that of the conventional air conditioning system (refrigerant cooling by using the outdoor air). Therefore, the increase in power consumption over that in the conventional air conditioning system is suppressed. Thus, under the environment with a high outdoor air temperature, the present air conditioning system demonstrates an energy saving effect higher than that in the conventional air conditioning system.

Further, in the third embodiment, when the unit configuration, manufacture, and installation are such as explained with reference to FIGS. 4 and 5A, it is possible to obtain the effect substantially identical to that of the second embodiment. Thus, the effects explained in relation to the second embodiment, namely, (a) compact configuration, (b) reduction of construction cost due to ductless configuration and wall mounting, (c) size reduction and improvement of manufacturability by stacked configuration, and (d) reduction in blow energy (blow power) and cost reduction by using shared fans, can be also obtained in the third embodiment.

The configuration of the third embodiment will be compared hereinbelow with the conventional configuration with reference to FIG. 7.

FIG. 7A shows the operation model of the air conditioning system of the third embodiment. This figure is substantially the same as FIG. 6A, and some components therein are omitted. The components identical to those in FIG. 6A are assigned with the same reference numerals and detailed explanation thereof is herein omitted.

In brief, a refrigeration cycle such as a vapor compression refrigeration cycle is realized by the condenser 141, evaporator 143, compressor 144, and expansion valve 145 shown in the figure. The indirect outdoor air cooling function is realized by the pump 146, liquid-gas heat exchanger 147, and liquid-gas heat exchanger 142 shown in the figure.

The liquid-gas heat exchanger 147, which is the component through which the outdoor air passes, is installed on the exterior side (outside the building), and the condenser 141, liquid-gas heat exchanger 142, and evaporator 143, which are the components through which the indoor air passes, are installed on the interior side (inside the building). The installation locations of other components are not particularly limited.

FIG. 7C shows the operation model of the conventional air conditioning system for comparison with the system shown in FIG. 7A.

As shown in the figures, at least with respect to the model examples shown in FIGS. 7A and 7C, the configuration of and the conventional configuration are practically identical, and only the installation positions of the condenser are different. Because of such a difference in the installation positions, the condenser in FIG. 7A is denoted by the reference numeral 141, whereas the condenser shown in FIG. 7C is denoted by the reference symbol 141′.

As shown in FIG. 7A, in the air conditioning system of the third embodiment, the condenser 141 is installed at a position through which the indoor air passes after passing through the heating element 140 (server or the like). Meanwhile, as shown in FIG. 7C, the condenser 141′ in the conventional air conditioning system is installed at a position through which the outdoor air passes. It is desirable that the outdoor air pass through the condenser 141′ after passing through the liquid-gas heat exchanger 147 (such configuration is not shown in the figure). In the example shown in the figure the indirect outdoor air cooling function is stopped (for example, the pump 146 is stopped), for example, because the outdoor air temperature is very high.

FIG. 7B is a temperature pattern diagram corresponding to the air conditioning system of the third embodiment shown in FIG. 7A.

FIG. 7D is a temperature pattern diagram corresponding to the conventional air conditioning system shown in FIG. 7C.

In FIGS. 7B and 7D, the encircling arrows connected to the heating element 140 (server or the like) indicate temperature variations relating to the indoor air. The arrows connected to the compressor 144 and the expansion valve 145 indicate temperature variations relating to the first refrigerant. Further, Q (Q1 a etc.) means the amount of heat, and L (Lpa etc.) means the power (amount of consumed power).

The portion surrounded by a dot line and assigned with the reference numeral 141 a in FIG. 7B represents temperature variations of the indoor air and refrigerant inside the condenser 141. Likewise, the portion surrounded by a dot line and assigned with the reference numeral 141 b in FIG. 7D represents temperature variations of the refrigerant inside the condenser 141′.

Further, the portion surrounded by a dot line and assigned with the reference numeral 142 a in FIG. 7B represents temperature variations of the indoor air inside the liquid-gas heat exchanger 142. Likewise, the portion surrounded by a dot line and assigned with the reference numeral 142 b in FIG. 7D represents temperature variations of the indoor air inside the liquid-gas heat exchanger 142 (however, as shown in the figure, the temperature of the indoor air does not change).

Further, the portion surrounded by a dot line and assigned with the reference numeral 143 a in FIG. 7B represents temperature variations of the indoor air and refrigerant inside the evaporator 143. Likewise, the portion surrounded by a dot line and assigned with the reference numeral 143 b in FIG. 7D represents temperature variations of the indoor air and refrigerant inside the evaporator 143.

In the configuration shown in FIG. 7B, the exchange of the amount of heat Q1 a is performed between the indoor air and the first refrigerant in the condenser 141. As a result, as shown by the reference numeral 141 a in the figure, the temperature of the indoor air rises and the temperature of the first refrigerant decreases to the temperature level of the return air (RA) shown in the figure. The return air (RA) is the indoor air serving as the return air from the heating element 140 (server or the like). As also explained with reference to FIG. 6A, this is the ideal temperature pattern diagram for simulation, and actually such a diagram is not obtained. For example, although the temperature of the first refrigerant greatly decreases, it does not decrease to the temperature level of the return air (RA) as shown in the figure and is somewhat higher than that.

When the indoor air then passes through the liquid-gas heat exchanger 142, the quantity of heat Q2 a is drawn by the indirect outdoor air cooling function (indirectly exchanges heat with the outdoor air, the heat is radiated to the exterior side (outside of the building)). As a result, the temperature of the indoor air drops to the temperature level of the outdoor air (OA), for example, as shown by the reference numeral 142 a in the figure.

Then, as shown by the reference numeral 143 a in the figure, the heat in an amount of Q3 a is drawn from the indoor air in the evaporator 143, and the temperature of the indoor air decreases to the temperature level of the supplied air (SA) shown in the figure. The supplied air (SA), as referred herein, is the indoor air (cold air) supplied to the heating element 140 (server or the like). The temperature of the refrigerant in the evaporator 143 decreases to the “J” level shown in the figure.

Meanwhile, as shown in FIG. 7D, in the conventional configuration, the indoor air heated by the amount of heat QH in the heating element 140 (server or the like) does not pass through the condenser 141′, and therefore the temperature thereof does not change (see the reference numeral 141 b). Further, in the example shown in FIG. 7C, since the indirect outdoor air cooling function is stopped, even through the air passes through the liquid-gas heat exchanger 142, the temperature thereof does not change (see the reference numeral 142 b) and remains at the temperature level of the return air (RA) shown in the figure. Then, as shown by the reference numeral 143 b in the figure, the heat in an amount of Q3 b is drawn from the indoor air in the evaporator 143, and the temperature of the indoor air decreases to the temperature level of the supplied air (SA) shown in the figure.

Meanwhile, the first refrigerant exchanges heat in an amount of Q1 b with the outdoor air in the condenser 141′ installed on the exterior side (outside the building), and the temperature of the first refrigerant decreases to the temperature level of the outdoor air (OA) shown in the figure. The temperature of the first refrigerant is then decreased by the expansion valve 145 to the “J” temperature level shown in the figure, and the first refrigerant is thereafter supplied to the evaporator 143.

In this case, as shown in FIGS. 7B and 7D, the temperature of the first refrigerant before it enters the expansion valve 145 is RA in FIG. 7B and OA in FIG. 7D, and RA<OA. In other words, in the third embodiment, the temperature of the first refrigerant before the expansion valve 145 is lower than that in the conventional configuration. As a result, as has already been mentioned hereinabove, power consumption of the refrigeration cycle in the third embodiment can be small. In other words, where the power (power consumption) (mainly, the power (power consumption) of the compressor 144) of the refrigeration cycle in the third embodiment is denoted by Lca and the power (power consumption) (mainly, the power (power consumption) of the compressor 144) of the refrigeration cycle in the conventional configuration is denoted by Lcb, as shown in the figure, the condition of Lcb>Lca is fulfilled. In other words, the temperature of the return air (RA) is lower than the temperature of the outdoor air (OA) as in the example shown in the figure.

However, in the example shown in FIG. 7, in the conventional configuration, the power of the indirect outdoor air cooling function is stopped and, therefore, the power consumption is “0”, whereas in the configuration of the third embodiment, the power (power consumption) Lpa of the indirect outdoor air cooling function is added. Therefore, in this example, when the condition of “Lcb>Lca+Lpa” is fulfilled, the air conditioning system of the third embodiment consumes less power than the conventional air conditioning system.

FIG. 10 is a simplified configuration diagram of the entire system including the air conditioning system of the third embodiment.

The air conditioning system of the third embodiment is not limited to the above-described example, and can be configured, for example, as shown in FIG. 10. The configuration shown in FIG. 10 uses the structural components of the example shown in FIG. 4 and those components are assigned with same reference numerals as shown in FIG. 4. As mentioned hereinabove, an example in which the components are stacked and integrated is not limiting. Therefore, for example, the configuration such as shown in FIG. 10 may be used.

In the example shown in FIG. 10, the air conditioning system of the third embodiment is assumed to be constituted by a heat pump 151 and a heat exchanger 152 shown in the figure. The heat pump 151 is constituted by the evaporator 91 d, compressor 92, condenser 91 b, and expansion valve 93, and the refrigerant circulates in the order of “evaporator 91 d→compressor 92→condenser 91 b→expansion valve 93→evaporator 91 d” through the refrigerant piping 95 connected to the aforementioned components.

The heat exchanger 152 is constituted by the liquid-gas heat exchangers 91 c and 81 b and the piping 96 connecting the heat exchangers (this configuration is not shown in the figure).

The cold air (indoor air) delivered from the heat pump 151 enters the server room through the under-floor space, cools the server device, and becomes the warm air. The warm air (indoor air) flows into the heat pump 151 through the attic space, passes through the condenser 91 b, whereby the temperature thereof is raised, and then flows into the heat exchanger 152. Indirect heat exchange is performed between the indoor air and outdoor air inside the heat exchanger 152, and the temperature of the indoor air decreases. The indoor air with the decreased temperature flows into the heat pump 151 and is cooled when passing through the evaporator 91 d. The resultant cold air is delivered into the under-floor space, as described hereinabove.

The fourth embodiment will be explained below.

FIG. 11 shows the configuration of the air conditioning system (variation 1) of the fourth embodiment.

FIG. 12 shows the configuration of the air conditioning system (variation 2) of the fourth embodiment.

FIG. 13 shows the operation model of the air conditioning system of the fourth embodiment.

First, the air conditioning system (variation 1) of the fourth embodiment will be explained with reference to FIG. 11. In FIG. 11, the components substantially same as those shown in FIG. 5B are assigned with the reference symbols same as those in FIG. 5B and the explanation thereof is herein omitted or simplified.

The air conditioning system (variation 1) of fourth embodiment that is shown in FIG. 11 is constituted by an outdoor air unit 160 and an indoor air unit 170. Those outdoor air unit 160 and the indoor air unit 170 are provided on the exterior side (outside the building) and interior side (inside the building), with the wall 1 being interposed therebetween, in a substantially the same manner as the outdoor air unit 110 and the indoor air unit 120 shown in FIG. 5B.

The manufacturing and installation methods of those outdoor air unit 160 and the indoor air unit 170 may be substantially identical to the manufacturing and installation methods of those outdoor air unit 110 and the indoor air unit 120 shown in FIGS. 5A and 5B. The same is true for the configuration shown in FIG. 12. Further, the air conditioning system of the fourth embodiment demonstrates the effect substantially identical to that of the air conditioning system of the third embodiment. In addition the specific effect of the fourth embodiment which is described hereinbelow is also obtained.

The outdoor air unit 160 has a stack 111. The stack 111 has a fan 111 a, a liquid-gas heat exchanger 111 b, and a condenser 111 c and is configured by stacking and integrating those components as shown in the figure. Those components are assigned with the reference symbols of the components of the stack 111 shown in FIG. 5B and the explanation thereof is herein omitted or simplified. The same is true for the configuration relating to the below-described three-way valve 112′.

An expansion valve 123 and a compressor 113 are each provided in either of the outdoor air unit 160 and the indoor air unit 170. In the example shown in the figure, the expansion valve 123 is provided in the indoor air unit 170, and the compressor 113 is provided in the outdoor air unit 160, but the embodiment is not limited to this example.

Further, in the same manner as shown in FIG. 5B, the expansion valve 123, compressor 113, condenser 111 c, and condenser 171 b are provided on the refrigerant piping 125 where the first refrigerant circulates. In the configuration shown in FIG. 11, the evaporator 172 is also provided on the refrigerant piping 125. The evaporator 172 will be described hereinbelow in greater detail.

In the configuration shown in FIG. 11, similarly to the configuration shown in FIG. 5B, a three-way valve 112′, which is an example of a switching device, is provided in the refrigerant piping 125 along the way thereof. The refrigerant piping 125 is branched from the three-way valve 112′ into a refrigerant piping 125 a and a refrigerant piping 125 b, which are shown in the figure. The three-way valve 112′ is provided at the rear stage (downstream side) of the condenser 111 c. The refrigerant piping (branch piping) 125 a is connected to the condenser 171 b in the indoor air unit 170 and merges with the refrigerant piping (branch piping) 125 b on the downstream side of the condenser 171 b (merges in the merging point R shown in the figure and then again becomes the single refrigerant piping 125). The refrigerant piping 125 after merging in the merging point R is connected to the expansion valve 123. Check valves 122 a and 122 b are provided, close to and before the merging point R in the refrigerant piping 125 a and the refrigerant piping 125 b, respectively. As a result, the counterflow of the first refrigerant is prevented.

In the configuration shown in FIG. 11, the components substantially the same as those shown in FIG. 5B are explained in a simple manner (obviously, with the exception of those components that are assigned with the reference numerals other than those in FIG. 5B, such as the evaporator 172).

In the configuration shown in FIG. 11, the stack 171 shown in the figure is provided on the indoor air unit 170 side. The stack 171 is constituted by a fan 171 a, a condenser 171 b, and a liquid-gas heat exchanger 171 c. The difference between the stack 171 and the stack 121 is that the stack 171 does not include the evaporator 121 d. Therefore, the fan 171 a, condenser 171 b, and liquid-gas heat exchanger 171 c shown in the figure are by themselves substantially the same as the fan 121 a, condenser 121 b, and liquid-gas heat exchanger 121 c in the stack 121.

The indoor air passes through in the order of condenser 171 b→liquid-gas heat exchanger 171 c because of the indoor air flow (shown by a one-dot-dash arrow in the figure) formed by the fan 121 a.

The configuration shown in the figure is an example, and the embodiment is not limited to this example. Basically, the stack 171 is provided inside the indoor air unit 170, and the stack 111 is provided in the outdoor air unit 160, but other components may be provided in either of the indoor air unit 170 and the outdoor air unit 160. Therefore, for example, the evaporator 172 may be provided on the outdoor air unit 160 side.

In the present configuration example, the evaporator 172 is provided, as shown in the figure, instead of using the configuration without the evaporator 121 d, as described hereinabove. In other words, in FIG. 5B, the evaporator 121 d is provided between the expansion valve 123 and the compressor 113 (it goes without saying, that the evaporator is provided on the refrigerant piping 125). By contrast, in the present configuration, the evaporator 172 is provided between the expansion valve 123 and the compressor 113 (on the refrigerant piping 125).

The evaporator 121 d and the evaporator 172 have different configurations. The evaporator 121 d can be considered as a liquid-gas heat exchanger and performs heat exchange between any refrigerant and air (indoor air) in the form of refrigerant evaporation. In other words, it is a typical evaporator suitable for a typical air conditioner (air conditioning device or the like).

By contrast, the evaporator 172 can be considered as a liquid-liquid heat exchanger, rather than the liquid-gas heat exchanger, of a well-known configuration. Therefore, the evaporator 172 does not perform heat exchange with the air (indoor air), which is gas. The evaporator 172 basically does not constitute part of the stack 171 through which the indoor air passes. The installation position of the evaporator 172 is not particularly specified, and it is basically assumed to be provided in the indoor air unit 170 or the outdoor air unit 160.

As mentioned hereinabove, the evaporator 172 is provided on the refrigerant piping 125. Therefore, the first refrigerant passes inside thereof (this is not shown in the figure). Furthermore, as shown in the figure, the evaporator 172 is connected not only to the refrigerant piping 125, but also to the piping 162. Similarly to the piping 126 shown in FIG. 5B, the piping 162 is by itself configured to circulate the second refrigerant (for example, water) in the liquid-gas heat exchanger 111 b of the outdoor air unit 160 and the liquid-gas heat exchanger 171 c of the indoor air unit 170. Similarly to the configuration shown in FIG. 5B, a pump 124 for circulating the second refrigerant is provided at a random location on the piping 162.

As mentioned hereinabove, the evaporator 172 is also connected to the piping 162. Not only the first refrigerant, but also the second refrigerant passes through in the evaporator 172. Basically, as shown in the figure, the configuration is used in which the evaporator 172 is provided before (on the upstream side) of the liquid-gas heat exchanger 171 c. As a result, as will be described hereinbelow, the second refrigerant cooled by the first refrigerant in the evaporator 172 flows into the liquid-gas heat exchanger 171 c located on the downstream side.

The difference between the example shown in the figure and the configuration in FIG. 5B is that the former is also additionally provided with a three-way valve 161, but the three-way valve 161 is not a mandatory component. The three-way valve 161 will be explained below.

As mentioned hereinabove, the first refrigerant and the second refrigerant pass through inside the evaporator 172 (the internal configuration thereof is not shown in the figure). Similarly to the case of the evaporator 121 d, the first refrigerant evaporates inside the evaporator 172, and in this case the heat is drawn from the surroundings (the surroundings are cooled). In the case of the evaporator 121 d, the air (indoor air) passes inside thereof and, therefore, the air (indoor air) is cooled. By contrast, in the case of the evaporator 172, the second refrigerant passes inside thereof, as mentioned hereinabove, and therefore the second refrigerant is cooled by the first refrigerant.

In the case of the configuration shown in FIG. 5B, the second refrigerant is basically cooled by heat exchange with the outdoor air in the liquid-gas heat exchanger 111 b of the outdoor air unit 110, and the second refrigerant cooled by the outdoor air is supplied into the liquid-gas heat exchanger 121 c of the indoor air unit 120. As a result, heat exchange between the second refrigerant and the indoor air is performed inside the liquid-gas heat exchanger 121 c, and the indoor air is cooled by the second refrigerant. Meanwhile, in the case of the configuration shown in FIG. 11, the second refrigerant is further cooled inside the evaporator 172, as mentioned hereinabove, before being supplied to the liquid-gas heat exchanger 171 c.

It can be also assumed that in the configuration shown in FIG. 5B, the air (indoor air) is directly cooled by the first refrigerant, whereas in the configuration shown in FIG. 11, air (indoor air) is indirectly cooled via the second refrigerant.

In the configuration shown in FIG. 11, the indoor air (return air; warm air) flowing into the indoor air unit 170 from the attic space, for example, shown in FIG. 1 via the indoor air inlet 128 is initially heated while passing through the condenser 171 b and thereafter cooled while passing through the liquid-gas heat exchanger 171 c. The cooled indoor air (cold air) is discharged from the indoor air outlet 127 and delivered into the under-floor space, for example, shown in FIG. 1. The cold air is thus supplied into the cooling object space (the space of server setting).

Further, the controller 130 controls the compressor 113 or the circulating pump 124 to control the flow rate of the first refrigerant or the second refrigerant, for example, so that the temperature of the cold air discharged from the indoor air outlet 127 becomes substantially equal to a predetermined set temperature (for example, 18° C.). The controller 130 controls, for example, the compressor 113 or the circulating pump 124, for example, via the a signal line 131 shown in the below-described FIG. 13.

The evaporator 172 is a “liquid-liquid heat exchanger” performing heat exchange between liquid with a relatively low temperature (first refrigerant) and liquid with a relatively high temperature (second refrigerant), more specifically, for example, the so-called “liquid-liquid plate-type heat exchanger”.

The configuration relating to the three-way valve 161 will be explained below.

The configuration shown in FIG. 5B requires that the second refrigerant exchange heat with the outdoor air by flowing into the liquid-gas heat exchanger 111 b. By contrast, the configuration shown in FIG. 11 uses the three-way valve 161 which makes it possible for the second refrigerant not to flow into the liquid-gas heat exchanger 111 b (to bypass the heat exchanger). In the case of the present configuration, the second refrigerant is cooled by the first refrigerant in the evaporator 172 even when no heat exchange with the outdoor air is performed.

The three-way valve 161 is a valve for dividing the flow path of the piping into two flow paths. This valve has three piping connection ports, one of which is for inflow (called “inlet”) and the other two are for outflow (called “outlets”). The three-way valve 161 is connected to the piping 162 and causes the second refrigerant circulated inside the piping 162 by the circulating pump 124 to flow in from the inlet and flow out from one of the two outlets. The piping 162 can be also assumed to be branched into two by the three-way valve 161, and branching into a branch piping 162 a and a branch piping 162 b can be considered.

One of the two outlets of the three-way valve 161 is connected to the branch piping 162 a and the other is connected to the branch piping 162 b. The branch piping 162 a passes through the liquid-gas heat exchanger 111 b and then merges with the branch piping 162 b in the merging point Q shown in the figure and again becomes a single piping 162, and this piping 162 is connected to the evaporator 172 of the last stage. Meanwhile, the branch piping 162 b is connected to and merges with the branch piping 162 a in the merging point Q.

Where the second refrigerant flows out from the three-way valve 161 on the branch piping 162 a, the second refrigerant passes through the liquid-gas heat exchanger 111 b and then flows into the evaporator 172. Meanwhile, where the second refrigerant flows out from the three-way valve 161 on the branch piping 162 b, the second refrigerant flows directly into the evaporator 172, without passing through the liquid-gas heat exchanger 111 b.

Basically, in a state in which the second refrigerant can be cooled by the outdoor air in the liquid-gas heat exchanger 111 b, the second refrigerant passes through the liquid-gas heat exchanger 111 b. In other words, for example, in a state in which “outdoor air temperature>temperature of the second refrigerant flowing into the liquid-gas heat exchanger 111 b”, the second refrigerant flows out of the three-way valve 161 into the branch piping 162 b (bypasses the liquid-gas heat exchanger 111 b). As a result, it is possible to avoid the situation in which the temperature of the second refrigerant is raised in the liquid-gas heat exchanger 111 b.

However, not being limited to such an example, a configuration which is not provided with the three-way valve 161 (that is, the piping 162 is not branched into two pieces of piping) may be also used. In other words, the configuration same as that shown in FIG. 5B may be used with respect to the second refrigerant so that the second refrigerant necessarily flows into the liquid-gas heat exchanger 111 b.

A check valve may be also provided in the branch piping 162 a before the merging point Q with the branch piping 162 b (such configuration is not shown in the figure). As a result, when the second refrigerant flows out from the three-way valve 161 into the branch piping 162 b, the second refrigerant can be prevented from flowing into the liquid-gas heat exchanger 111 b.

The air conditioning system (variation 2) of the fourth embodiment shown FIG. 12 will be explained below.

The configuration shown in FIG. 12 can be considered as a modification of the configuration shown in FIG. 11 and is substantially the same as the configuration shown in FIG. 11, while being only partially different therefrom. Therefore, the explanation of the components in FIG. 12 that are substantially the same as those shown in FIG. 11 is omitted or simplified. The relationship (difference) between the configurations in FIG. 11 and FIG. 12 may be considered to be the same as that between the configurations shown in FIGS. 5A and 5B.

Thus, the configuration shown in FIG. 12 differs from that shown in FIG. 11 in that a three-way valve is installed on the refrigerant piping 125. The configuration shown in FIG. 12 is constituted by an outdoor air unit 160′ and an indoor air unit 170. The indoor air unit may be the same as the indoor air unit 170 shown in FIG. 11 and is, therefore, assigned with the same reference numeral “170”. Meanwhile, the outdoor air unit is somewhat different from the outdoor air unit 160 shown in FIG. 11 and is, therefore, assigned with the reference numeral “160′”.

Similarly to the configuration shown in FIG. 5B, in the outdoor air unit 160 shown in FIG. 11, a three-way valve 112′ is provided on the outflow side (downstream side) of the condenser 111 c, and the first refrigerant is necessarily caused to flow through the condenser 111 c. The three-way valve 112′ controls whether or not to cause also the first refrigerant to flow through the condenser 171 b.

Meanwhile, similarly to the configuration shown in FIG. 5A, in outdoor air unit 160′ shown in FIG. 12, a three-way valve 112 is provided on the inflow side (upstream side) of the condenser 111 c. The first refrigerant is switched by the three-way valve 112 in either of the “state in which the first refrigerant passes through the condenser 111 c, but does not pass through the condenser 121 b” and the “state in which the first refrigerant does not pass through the condenser 111 c, but passes through the condenser 121 b”.

The configuration shown in FIG. 12 is explained hereinabove in a simple manner only with respect to the differences between this configuration and that shown in FIG. 11. The functions and effects of the configuration shown in FIG. 12 are substantially the same as those of the configuration shown in FIG. 11.

FIG. 13 is explained hereinbelow.

FIG. 13A shows the operation model of the above-described air conditioning system of the fourth embodiment. Further, FIG. 13B shows the simulation results relating to the reduction in power consumption in the fourth embodiment.

First, FIG. 13A will be explained. Similarly to FIG. 6A, each temperature shown in FIG. 13A indicates an example based on the simulation result and is not limited to this example.

FIG. 13A corresponds to the configuration example shown in FIG. 12 and includes reference numerals of the components shown in FIG. 12. However, the heating element 140 shown in the figure is the heating element 140 shown in FIG. 6A and corresponds, for example, to the heating element 101 (server device or the like) shown in FIG. 1. FIG. 13A is assumed to correspond to the case in which in the configuration shown in FIG. 12, a state is assumed such that the three-way valve 112 does not allow the first refrigerant to pass through the condenser 111 c side. Therefore, the condenser 111 c is not shown in FIG. 13A, and the condenser 171 b is shown on the downstream side of the compressor 113.

As shown by a thick-line arrow in FIG. 13A, the interior air (indoor air) circulates through the heating element 140, condenser 171 b, and liquid-gas heat exchanger 171 c.

Further, the first refrigerant circulates in the configuration provided on the refrigerant piping 125 shown in the figure. Thus, as shown by a thin-line arrow in the figure, the first refrigerant circulates in the compressor 113, condenser 171 b, expansion valve 123, and evaporator (liquid-liquid heat exchanger) 172.

The second refrigerant circulates in the components on the piping 162 shown in the figure. Thus, as shown by a thin dash-dot-dash arrow in the figure, the second refrigerant circulates in the circulating pump 124, liquid-gas heat exchanger 171 c, liquid-gas heat exchanger 111 b, and evaporator (liquid-liquid heat exchanger) 172.

The indoor air that has been cooled to 32° C. by cooling the heating element 140 in a substantially the same manner as shown in FIG. 6A passes through the condenser 171 b, whereby the temperature of the indoor air rises to 55° C. The indoor air with a temperature of 55° C. is cooled by heat exchange with the second refrigerant and the temperature of the indoor air drops (to 18° C. in the example shown in the figure) when the indoor air passes through the liquid-gas heat exchanger 171 c. This indoor air with a temperature of 18° C. is delivered, for example, to the under-floor space shown in FIG. 1, whereby the heating element 140 is cooled.

In the case shown in FIG. 6A, the indoor air with a temperature of 55° C. is cooled by heat exchange with the second refrigerant and the temperature of the indoor air drops when the indoor air passes through the liquid-gas heat exchanger 142, but since the temperature of the second refrigerant is affected by the outdoor air temperature (for example, 36° C.), the temperature of the indoor air cannot be reduced to a set temperature (18° C. or the like). The temperature of the indoor air is reduced to the set temperature (18° C. or the like) by the last-stage evaporator 143.

By contrast, in the example shown in FIG. 13A, the temperature of the second refrigerant can be made lower than the outdoor air temperature (equal to or less than the set temperature; 18° C. in the present example) by the evaporator (liquid-liquid heat exchanger) 172, and the temperature of the indoor air can be reduced to the set temperature (18° C. or the like) in the liquid-gas heat exchanger 171 c.

In this case, as mentioned hereinabove (and as shown in FIG. 13A), both the first refrigerant and the second refrigerant pass through the evaporator (liquid-liquid heat exchanger) 172, and the first refrigerant and the second refrigerant exchange heat inside the evaporator 172. In the example shown in the figure, the temperature of the first refrigerant flowing into the evaporator 172 is 10° C. Meanwhile, the temperature of the second refrigerant flowing out of the evaporator 172 (in other words, the temperature of the second refrigerant after heat exchange with the first refrigerant) is 18° C.

Here, the temperature of the second refrigerant flowing into the evaporator 172 is not shown in the figure, but because the second refrigerant flows into the evaporator 172 after undergoing heat exchange with the outdoor air (36° C.) in the liquid-gas heat exchanger 111 b, the temperature of the second refrigerant flowing into the evaporator 172 is basically not less than the outdoor air temperature (36° C.). In other words, in the example shown in the figure, heat exchange between the first refrigerant at a temperature of 10° C. and the second refrigerant with a temperature equal to or higher than 36° C. is performed in the evaporator 172. Therefore, the second refrigerant is obviously cooled by the first refrigerant, and in the example shown in the figure, the second refrigerant is cooled to 18° C. as described hereinabove.

The temperature of the second refrigerant (denoted by temperature Ta) flowing from the liquid-gas heat exchanger 171 c also differs depending on the flow rate of the second refrigerant (this relationship is not shown in the figure). In other words, when the flow rate of the second refrigerant is small, the temperature Ta can become, for example, a temperature (e.g., equal to or higher than 50° C.) close to the indoor air temperature (55° C.). Meanwhile, when the flow rate of the second refrigerant is high, the temperature Ta can become lower than the outdoor air temperature (36° C.)

With consideration for such a case, the configuration provided with the three-way valve 161 can be also suggested. Thus, for example, when “Ta<outdoor air temperature”, the controller 130 may control the three-way valve 161 to obtain a state in which the second refrigerant bypasses (does not pass through) the liquid-gas heat exchanger 111 b.

In such a case, a “mixing/stirring unit” (not shown in the figure) may be provided at the last stage (downstream side with respect to the indoor air) of the liquid-gas heat exchanger 171 c. The “mixing/stirring unit” has a well-known configuration and is, therefore, neither explained nor shown in the figure herein. This unit is configured to obtain a substantially uniform temperature distribution of gas such as air therein by mixing/stirring inside the unit. In other words, the temperature of the indoor air (cold air) flowing from the liquid-gas heat exchanger 171 c is taken as 18° C., as described hereinabove, and it means the temperature in the case in which the temperature distribution is substantially uniform. However, the temperature distribution is actually not substantially uniform, and it can be assumed that there are portions with a low temperature and portions with a high temperature (relative to 18° C.). Therefore, the configuration in which the “mixing/stirring unit” (not shown in the figure) is provided to obtain a substantially uniform temperature distribution may be also used.

It is also possible that when the cold air reaches the heating element 140, the temperature distribution of the cold air is substantially uniform due to natural mixing taking place as the cold air flows in the under-floor space. Therefore, in some cases, it is not necessary to provide the “mixing/stirring unit” (not shown in the figure).

The configuration relating to the refrigeration cycle in which the first refrigerant circulates (the refrigerant piping 125 and various components provided on the refrigerant piping 125) can be considered to be substantially the same as the configuration shown in FIG. 6A, except that the evaporator (liquid-gas heat exchanger) 143 is replaced with the evaporator (liquid-liquid heat exchanger) 172. Accordingly, where such a configuration is explained in a simple manner, the first refrigerant assumes a temperature of 25° C. due to heat exchange with the second refrigerant in the evaporator (liquid-liquid heat exchanger) 172 and is then heated to 66° C. by compression in the compressor 113. Such first refrigerant with a temperature of 66° C. is reduced in temperature (to 32° C.) by heat exchange with the indoor air in the condenser 171 b and then further reduced in temperature (to 10° C.) by the expansion valve 123. The first refrigerant with a temperature of 10° C. exchanges heat with the second refrigerant in the evaporator 172 as described hereinabove.

The simulation results shown in FIG. 13B will be explained below.

In the graph shown in FIG. 13B, similarly to the graph shown in FIG. 6B, the outdoor air temperature (° C.) is plotted against the abscissa, and the consumed power (kW) is plotted against the ordinate. Hollow circles (∘) in the graph represent data for the conventional system, and full circles () represent data for the air conditioning system of the fourth embodiment. Those data correspond to “total power consumption” in FIG. 6B. The conventional air conditioning system is, for example, the air conditioning system shown in FIG. 14, but the embodiment is not being limited to this example, and it can be also considered, for example, as the air conditioning system of the first embodiment or the second embodiment.

As shown in the figure, where the outdoor air temperature is comparatively low, the power consumption of the conventional air conditioning system is not substantially different from that of the present air conditioning system (air conditioning system of the fourth embodiment).

However, where the outdoor air temperature becomes higher than a certain level (referred to as a high-temperature range; for example, a level of above 30° C. can be selected as a criterion), the total power consumption in the conventional air conditioning system rises rapidly with the increase in temperature, as shown in the figure.

Meanwhile, in the air conditioning system of the fourth embodiment, even in the high-temperature range, the power consumption increases gradually with the increase in outdoor air temperature in a substantially the same manner as at a lower temperature and does not increase rapidly. For this reason, in the high-temperature range, as shown in the figure, the difference in total power consumption between the conventional air conditioning system and the present air conditioning system increases as the outdoor air temperature rises.

Thus, under the environment in which the outdoor air temperature is higher than a certain level, the power consumption of the air conditioning system of the fourth embodiment is lower than that of the conventional air conditioning system, and the energy saving effect increases with the increase in outdoor air temperature.

The example of configuration illustrated by FIGS. 11 and 12 is one example of the present invention and is not being limited to this. For example, FIG. 9 shows a modification of the configuration shown in FIG. 5A, and a similar modification may be also considered with respect to the configuration shown in FIGS. 11 and 12. This modification is not shown in the figure, but can be clearly understood from the relationship between FIG. 5A and FIG. 9.

With the above-described air conditioning system (variation 1) and (variation 2) of the fourth embodiment, the following effects can be obtained in addition to the effects that are substantially the same as those obtained in the above-described air conditioning system of the third embodiment.

-   -   The evaporator (evaporator 121 d etc.) of the other examples is         a liquid-gas heat exchanger that performs heat exchange between         the air (indoor air) and liquid (first refrigerant), whereas the         evaporator 172 is, as mentioned hereinabove, a liquid-liquid         heat exchanger. The heat exchange efficiency in the         liquid-liquid heat exchanger is typically higher than that in a         liquid-gas heat exchanger. Therefore, where the heat exchange         capacity is assumed to be the same, the liquid-liquid heat         exchanger can be made smaller than the liquid-gas heat exchanger         (for example, the volume of the evaporator 172 can be about 5%         to 10% that of the evaporator 121 d).     -   In the third embodiment, two heat exchangers (for example, in         FIGS. 5A sand 5B, the liquid-gas heat exchanger 121 c and the         evaporator 121 d) are provided on the path where the indoor air         flows. By contrast, in the configuration shown in FIGS. 11 and         12, the evaporator 121 d is removed and the evaporator 172 is         not provided on the path where the indoor air flows. Since the         evaporator 121 d is thus removed, the flow pressure loss of the         indoor air is reduced whereby the flow efficiency is increased.         This results, for example, in reduced power consumption in the         fan 171 a and the like.

The evaporator 121 d and the evaporator 172 both perform cooling with the first refrigerant, but the evaporator 121 d cools the air, whereas the evaporator 172 cools the liquid (second refrigerant). Since the cooling medium is liquid which has thermal capacity higher than the air, temperature variations become smooth and temperature control is stabilized.

For example, let us assume a case in which the temperature of the first refrigerant temporarily changes significantly for some reason. In such a case, in the conventional system, the temperature of the air (indoor air) that is directly cooled by the first refrigerant also changes significantly. By contrast, in the present system, the temperature of the second refrigerant changes, but the temperature variations become gradual (in comparison with the case of air) and, therefore, temperature variations of the air (indoor air) that is cooled by the second refrigerant also become gradual. As a result, temperature control can be easily performed to maintain the indoor air temperature close to the set value (for example, 18° C.)

When the outdoor air temperature is high (for example, the case in which the temperature of the second refrigerant flowing into the liquid-gas heat exchanger 111 b is less than the outdoor air temperature), the second refrigerant is caused by the three-way valve 161 to circulate so as to bypass the liquid-gas heat exchanger 111 b. As a result, the event in which the second refrigerant is heated by the outdoor air and raised in temperature can be avoided.

With the air conditioning system using outdoor air in accordance with the present invention, and the indoor air unit and outdoor air unit thereof, it is possible to provide an air conditioning system in which the interior air is cooled with low energy consumption by using outdoor air and the indoor air cooling using outdoor air can be realized even when the outdoor air temperature is high, and it is also possible to reduce energy consumption in an air conditioning system with a compression-type refrigeration cycle. 

1-19. (canceled)
 20. An air conditioning system using outdoor air, the air conditioning system defining an interior side as an inside of a building having indoor air, and an exterior side as an outside of the building having the outdoor air, comprising: a first heat exchanger disposed on the interior side; an evaporator disposed on the interior side; a condenser disposed on the interior side; a first fan disposed on the interior side for passing the indoor air through the first heat exchanger, the evaporator and the condenser, wherein the evaporator, the first heat exchanger and the condenser are arranged in this order along passage of the indoor air by the first fan; a second heat exchanger disposed on the exterior side; a second fan disposed on the exterior side for passing the outdoor air through the second heat exchanger; an expansion valve provided on either the exterior side or the interior side; a compressor provided on either the exterior side or the interior side; a first piping connected to the evaporator, the condenser, the expansion valve, and the compressor, for circulating a first refrigerant through the first piping to the evaporator, the condenser, the expansion valve and the compressor to perform a compression refrigeration cycle, thereby forming an air conditioner; and a second piping connected to the first heat exchanger and the second heat exchanger, a second refrigerant being circulated through the second piping to the first heat exchanger and the second heat exchanger, the second refrigerant and an indoor air that has passed through the condenser being heat exchanged by the first heat exchanger, to thereby cool the indoor air, and the second refrigerant being cooled by the outside air by heat exchanging the inside air with the second refrigerant that has been cooled in the second heat exchanger, thereby forming an indirect outdoor air cooler.
 21. An air conditioning system using outdoor air, comprising: an indoor air unit for passing through indoor air, having: a first heat exchanger; an evaporator; a condenser; and a first fan for passing the indoor air through the first heat exchanger, the evaporator, and the condenser, the condenser, the first heat exchanger and the evaporator being arranged in this order from an upstream side of an indoor air flown by the first fan; an outdoor air unit for passing through the outdoor air, having: a second heat exchanger; and a second fan for passing the outdoor air through the second heat exchanger; an expansion valve provided on either one of the outdoor air unit or the indoor air unit; a compressor provided on either one of the outdoor air unit or the indoor air unit; a first piping connected to the evaporator, the condenser, the expansion valve, and the compressor, for circulating a first refrigerant through the first piping to the evaporator, condenser, expansion valve and compressor, to form an air conditioner by a compression refrigeration cycle; and a second piping connected to the first heat exchanger and the second heat exchanger, a second refrigerant being circulated through the second piping to the first heat exchanger and the second heat exchanger, the second refrigerant and an indoor air that has passed through the condenser being heat exchanged by the first heat exchanger, to thereby cool the indoor air by the second refrigerant, and the second refrigerant being cooled by the outside air by heat exchanging the inside air with the second refrigerant that has been cooled in the second heat exchanger, thereby forming an indirect outdoor air cooler.
 22. An air conditioning system using outdoor air according to claim 21, wherein the indoor air as a warm air flowing into the indoor air unit and increasing a temperature in a cooling object space is further heated by heat radiation from the condenser when passing through the condenser and decreases a temperature of the first refrigerant.
 23. An air conditioning system using outdoor air according to claim 22, wherein a temperature of the indoor air raised in the condenser is decreased by the heat exchange of the indoor air with the second refrigerant when passing through the first heat exchanger, and the indoor air is then cooled when passing through the evaporator, becoming cold air, and is supplied into the cooling object space; and the first refrigerant reduced in temperature in the condenser circulates in an order of the expansion valve and the evaporator, and cools the indoor air passing through the evaporator in the evaporator.
 24. An air conditioning system using outdoor air according to claim 21, wherein the outdoor air unit further comprises: a second condenser; a branch piping branching off from the first piping and connected to the second condenser; and a switching device provided in a branching point of the first piping, for circulating the first refrigerant in either the condenser in the indoor air unit or the second condenser in the outdoor air unit.
 25. An air conditioning system using outdoor air according to claim 21, wherein the outdoor air unit further comprises: a second condenser connected to the first piping; and a switching device disposed in a branching point in which the first piping is branched on a refrigerant outflow side of the second condenser, wherein the switching device switches routes for circulating the first refrigerant to either a first route for circulating the first refrigerant in the condenser in the indoor air unit and then circulating in the expansion valve, or a second route for circulating the first refrigerant in the expansion valve without circulating in the condenser in the indoor air unit.
 26. An air conditioning system using outdoor air according to claim 24, wherein the second heat exchanger is provided on an upstream side of an outdoor air flow formed by the second fan, and the second condenser is provided on a downstream side of the outdoor air flow.
 27. An air conditioning system using outdoor air according to claim 24, wherein the switching device circulates the first refrigerant in the condenser when an outdoor air temperature is high and in the second condenser when the outdoor air temperature is low.
 28. An air conditioning system using outdoor air according to claim 25, wherein the switching device circulates the first refrigerant in the first route when the outdoor air temperature is higher than an indoor air temperature.
 29. An indoor air unit for an air conditioning system using outdoor air, which is disposed on an interior side of a building to pass an indoor air therethrough and adapted to correspond to an outdoor air unit disposed on an exterior side of the building to pass an outdoor air therethrough, comprising: a first heat exchanger; an evaporator; a condenser; a first fan for passing the indoor air through the first heat exchanger, the evaporator, and the condenser, wherein the evaporator, the first heat exchanger, and the condenser are arranged in this order along passage of the indoor air by the first fan; an expansion valve formed in the indoor air unit; a compressor formed in the indoor air unit; a first piping connected to the compressor, wherein an air conditioner comprises the evaporator, the condenser, the expansion valve and a part of the first piping, and a first refrigerant passes the evaporator, the condenser, the expansion valve and the compressor through the first piping to perform a compression refrigeration cycle; and a second piping adapted to connect the first heat exchanger to a second heat exchanger of the outdoor air unit, a second refrigerant being circulated through the second piping to the first heat exchanger and the second heat exchanger, and in the first heat exchanger, the indoor air being heat exchanged by the second refrigerant that has been cooled and the outdoor air, to thereby cool the second refrigerant by the outdoor air.
 30. An outdoor air unit for an air conditioning system using outdoor air, which is disposed on an outdoor side of a building to pass an outdoor air therethrough and adapted to correspond to an indoor air unit disposed on an interior side of the building to pass an indoor air therethrough, comprising: a second heat exchanger and a second fan for passing the outdoor air through the second heat exchanger; an expansion valve; a compressor; a first piping connected to the compressor, wherein an air conditioner is adapted to comprise the evaporator, the condenser formed in the indoor air unit, the expansion valve and a part of the first piping, and a first refrigerant passes the evaporator, the condenser, the expansion valve and the compressor through the first piping to perform a compression refrigeration cycle; and a second piping adapted to connect the second heat exchanger to a first heat exchanger of an indoor air unit, a second refrigerant being circulated through the second piping to the first heat exchanger and the second heat exchanger, and in the second heat exchanger, the indoor air being heat exchanged by the second refrigerant that has been cooled and an outdoor air being heat, to thereby cool the second refrigerant by the outdoor air.
 31. A stack for cooling indoor air, which is disposed on an interior side of a building to pass an indoor air therethrough and adapted to correspond to an outdoor air unit disposed on an exterior side of the building to pass an outdoor air therethrough, comprising: a condenser for performing a compression refrigeration cycle using a first refrigerant, and passing the indoor air therethrough as warm air flowing into the indoor air unit and raising a temperature in a cooling object space, said condenser performing a heat radiation to raise a temperature of the indoor air and decreasing a temperature of the first refrigerant; a first heat exchanger for passing a second refrigerant therethrough that was subject to a heat exchange with the outdoor air in the outdoor air unit and the indoor air in which a temperature was increased in the condenser, and inducing a heat exchange between the second refrigerant and the indoor air; an evaporator for performing the compression refrigeration cycle together with the condenser; and a first fan, wherein the condenser, the first heat exchanger, the evaporator, and the first fan are stacked and integrated.
 32. A stack for moving heat of indoor air to outdoor air, which is disposed on an outdoor side of a building to pass an outside air therethrough and adapted to correspond to an indoor air unit disposed on an interior side of the building to pass an interior air therethrough, comprising: a second heat exchanger for passing therethrough the outdoor air and a second refrigerant subject to a heat exchange with the indoor air in the indoor air unit, and inducing a heat exchange between the second refrigerant and the outdoor air; and a second fan, wherein the second heat exchanger and the second fan are stacked and integrated.
 33. An air conditioning system using outdoor air, the air conditioning system defining an interior side as an inside of a building having indoor air, and an exterior side as an outside of the building having the outdoor air, comprising: a first heat exchanger disposed on the interior side; a condenser disposed on the interior side; and a first fan disposed on the interior side, for passing the indoor air through the first heat exchanger and the condenser, wherein the condenser and the first heat exchanger are provided in an order from an upstream side of an indoor air flow formed by the first fan; an evaporator disposed either on the exterior side or the interior side, an expansion valve disposed either on the exterior side or the interior side, a compressor disposed either on the exterior side or the interior side; a first piping connected to the compressor disposed either on the exterior side or the interior side, a first refrigerant being circulated through the first piping to the evaporator, the condenser, the expansion valve and the compressor to perform a compression refrigeration cycle; and a second piping connected to the first heat exchanger and the evaporator, a second refrigerant being circulated through the second piping to the first heat exchanger and the evaporator, the second refrigerant being cooled by the first refrigerant by heat exchanging the first refrigerant and the second refrigerant at the evaporator, and in the first heat exchanger, the inside air being cooled by the second refrigerant by heat exchanging the inside air with the second refrigerant that has been cooled, thereby forming an indirect outdoor air cooler.
 34. An air conditioning system using outdoor air, comprising: an indoor air unit for passing indoor air therethrough, including: a first heat exchanger; a condenser; and a first fan for passing the indoor air through the first heat exchanger and the condenser, wherein the indoor air unit is configured in an order of the condenser and the first heat exchanger from an upstream side of an indoor air flow formed by the first fan; an outdoor air unit for passing the outdoor air therethrough; an evaporator disposed either in the outdoor air unit or the indoor air unit; an expansion valve disposed either in the outdoor air unit or the indoor air unit; a compressor disposed either in the outdoor air unit or the indoor air unit; a first piping connected to the compressor, wherein a first refrigerant is circulated through the condenser, the evaporator, the expansion valve, and the compressor, to perform a compression refrigeration cycle; and a second piping connected to the first heat exchanger and the evaporator, a second refrigerant being circulated through the second piping to the first heat exchanger and the evaporator, the second refrigerant being cooled by the first refrigerant by heat exchanging the first refrigerant and the second refrigerant at the evaporator, and in the first heat exchanger, the inside air being cooled by the second refrigerant by heat exchanging the inside air with the second refrigerant that has been cooled, thereby forming an indirect outdoor air cooler.
 35. An air conditioning system using outdoor air according to claim 33, further comprising: a second heat exchanger disposed on the exterior side or in the outdoor air unit, and connected to the second piping; and a second fan for passing the outdoor air through the second heat exchanger; wherein the second refrigerant exchanges heat with the outdoor air in the second heat exchanger and then exchanges heat with the first refrigerant in the evaporator.
 36. An air conditioning system using outdoor air according to claim 35, wherein the second piping includes a switching device to divide the second piping into two branch pipes and to flow the second refrigerant to one of the two branch pipes, one of the branch pipes being connected to the second heat exchanger; and the switching device is capable of switching between a state in which the second refrigerant is circulated in the second heat exchanger, and a state in which the second refrigerant is not circulated in the second heat exchanger.
 37. An air conditioning system using outdoor air according to claim 33, wherein the first heat exchanger is a liquid-gas heat exchanger, and the evaporator is a liquid-liquid heat exchanger.
 38. An indoor air unit for an air conditioning system using outdoor air, which is disposed on an interior side of a building to pass an indoor air therethrough and adapted to correspond to an outdoor air unit disposed on an exterior side of the building to pass an outdoor air therethrough, comprising: a first heat exchanger; a condenser; a first fan for passing the indoor air through the first heat exchanger and the condenser, wherein the condenser and the first heat exchanger are arranged in an order from an upstream side of a flow of the indoor air formed by the first fan; an evaporator; an expansion valve; a compressor; a first piping connected to the compressor, wherein a first refrigerant is circulated through the condenser, the evaporator, the expansion valve, and the compressor to perform a compression refrigeration cycle; and a second piping connected to the first heat exchanger and the evaporator, a second refrigerant being circulated through the second piping to the first heat exchanger and the evaporator, the second refrigerant being cooled by the first refrigerant by heat exchanging the first refrigerant and the second refrigerant in the evaporator, and in the first heat exchanger, the indoor air being heat exchanged by the second refrigerant that has been cooled and the indoor air to cool the indoor air by the second refrigerant, thereby forming an indirect outdoor air cooler. 